Hi, I'm Treeston, and welcome to Combat PR Prep Refactors.

Today, we're moving UNIT_FLAG_IMMUNE_TO_PC and UNIT_FLAG_IMMUNE_TO_NPC to higher-level abstraction so combat manager can react to it.
New methods on Unit:
- void SetImmuneTo<All/PC/NPC>(apply, keepCombat = false);
- bool IsImmuneTo<All/PC/NPC>() const;

40 files changed, 169 insertions, 115 deletions

diff --git a/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/boss_general_zarithrian.cpp b/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/boss_general_zarithrian.cpp
index d835549ad17..99d30e4dc0f 100644
--- a/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/boss_general_zarithrian.cpp
+++ b/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/boss_general_zarithrian.cpp
@@ -77,7 +77,10 @@ class boss_general_zarithrian : public CreatureScript
             {
                 _Reset();
                 if (instance->GetBossState(DATA_SAVIANA_RAGEFIRE) == DONE && instance->GetBossState(DATA_BALTHARUS_THE_WARBORN) == DONE)
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                {
+                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(false);
+                }
             }
 
             bool CanAIAttack(Unit const* target) const override
diff --git a/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/instance_ruby_sanctum.cpp b/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/instance_ruby_sanctum.cpp
index db2fc0b407b..9b48e717f75 100644
--- a/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/instance_ruby_sanctum.cpp
+++ b/src/server/scripts/Northrend/ChamberOfAspects/RubySanctum/instance_ruby_sanctum.cpp
@@ -175,7 +175,10 @@ class instance_ruby_sanctum : public InstanceMapScript
             {
                 if (GetBossState(DATA_SAVIANA_RAGEFIRE) == DONE && GetBossState(DATA_BALTHARUS_THE_WARBORN) == DONE)
                     if (Creature* zarithrian = GetCreature(DATA_GENERAL_ZARITHRIAN))
-                        zarithrian->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                    {
+                        zarithrian->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                        zarithrian->SetImmuneToPC(false);
+                    }
             }
 
             void SetData(uint32 type, uint32 data) override
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheChampion/boss_grand_champions.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheChampion/boss_grand_champions.cpp
index 4bb64f22dfc..08214a5195d 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheChampion/boss_grand_champions.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheChampion/boss_grand_champions.cpp
@@ -111,11 +111,10 @@ void AggroAllPlayers(Creature* temp)
 
             if (player->IsAlive())
             {
-                temp->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                temp->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                temp->SetImmuneToPC(true);
                 temp->SetReactState(REACT_AGGRESSIVE);
-                temp->SetInCombatWith(player);
-                player->SetInCombatWith(temp);
-                temp->GetThreatManager().AddThreat(player, 0.0f);
+                temp->EngageWithTarget(player);                
             }
         }
     }
@@ -330,7 +329,8 @@ public:
 
             me->SetReactState(REACT_PASSIVE);
             // THIS IS A HACK, SHOULD BE REMOVED WHEN THE EVENT IS FULL SCRIPTED
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(true);
         }
 
         void Initialize()
@@ -467,7 +467,8 @@ public:
 
             me->SetReactState(REACT_PASSIVE);
             // THIS IS A HACK, SHOULD BE REMOVED WHEN THE EVENT IS FULL SCRIPTED
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(true);
         }
 
         void Initialize()
@@ -610,7 +611,8 @@ public:
 
             me->SetReactState(REACT_PASSIVE);
             // THIS IS A HACK, SHOULD BE REMOVED WHEN THE EVENT IS FULL SCRIPTED
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(true);
         }
 
         void Initialize()
@@ -761,7 +763,8 @@ public:
 
             me->SetReactState(REACT_PASSIVE);
             // THIS IS A HACK, SHOULD BE REMOVED WHEN THE EVENT IS FULL SCRIPTED
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(true);
         }
 
         void Initialize()
@@ -921,7 +924,8 @@ public:
 
             me->SetReactState(REACT_PASSIVE);
             // THIS IS A HACK, SHOULD BE REMOVED WHEN THE EVENT IS FULL SCRIPTED
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(true);
         }
 
         void Initialize()
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_faction_champions.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_faction_champions.cpp
index 433721e70bd..fc2d5c466cc 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_faction_champions.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_faction_champions.cpp
@@ -488,7 +488,8 @@ class boss_toc_champion_controller : public CreatureScript
                     {
                         _summons.Summon(champion);
                         champion->SetReactState(REACT_PASSIVE);
-                        champion->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        champion->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                        champion->SetImmuneToPC(false);
                         if (playerTeam == ALLIANCE)
                         {
                             champion->SetHomePosition(vChampionJumpTarget[pos].GetPositionX(), vChampionJumpTarget[pos].GetPositionY(), vChampionJumpTarget[pos].GetPositionZ(), 0);
@@ -519,7 +520,8 @@ class boss_toc_champion_controller : public CreatureScript
                             if (Creature* summon = ObjectAccessor::GetCreature(*me, *i))
                             {
                                 summon->SetReactState(REACT_AGGRESSIVE);
-                                summon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                                summon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                                summon->SetImmuneToPC(false);
                             }
                         }
                         break;
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_lord_jaraxxus.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_lord_jaraxxus.cpp
index 767f46756ea..8f50ed0e365 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_lord_jaraxxus.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_lord_jaraxxus.cpp
@@ -121,7 +121,8 @@ class boss_jaraxxus : public CreatureScript
                 _JustReachedHome();
                 instance->SetBossState(BOSS_JARAXXUS, FAIL);
                 DoCast(me, SPELL_JARAXXUS_CHAINS);
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                me->SetImmuneToPC(true);
             }
 
             void KilledUnit(Unit* who) override
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_northrend_beasts.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_northrend_beasts.cpp
index 81cd4ff8470..17ce9458905 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_northrend_beasts.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_northrend_beasts.cpp
@@ -205,7 +205,8 @@ class boss_gormok : public CreatureScript
                 {
                     case 0:
                         instance->DoUseDoorOrButton(instance->GetGuidData(GO_MAIN_GATE_DOOR));
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->SetReactState(REACT_AGGRESSIVE);
                         me->SetInCombatWithZone();
                         break;
@@ -614,7 +615,8 @@ struct boss_jormungarAI : public BossAI
                 case EVENT_SUMMON_ACIDMAW:
                     if (Creature* acidmaw = me->SummonCreature(NPC_ACIDMAW, ToCCommonLoc[9].GetPositionX(), ToCCommonLoc[9].GetPositionY(), ToCCommonLoc[9].GetPositionZ(), 5, TEMPSUMMON_MANUAL_DESPAWN))
                     {
-                        acidmaw->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        acidmaw->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        acidmaw->SetImmuneToPC(false);
                         acidmaw->SetReactState(REACT_AGGRESSIVE);
                         acidmaw->SetInCombatWithZone();
                         acidmaw->CastSpell(acidmaw, SPELL_EMERGE);
@@ -771,7 +773,8 @@ class boss_dreadscale : public CreatureScript
                 {
                     case 0:
                         instance->DoCloseDoorOrButton(instance->GetGuidData(GO_MAIN_GATE_DOOR));
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->SetReactState(REACT_AGGRESSIVE);
                         me->SetInCombatWithZone();
                         break;
@@ -944,7 +947,8 @@ class boss_icehowl : public CreatureScript
                         break;
                     case 2:
                         instance->DoUseDoorOrButton(instance->GetGuidData(GO_MAIN_GATE_DOOR));
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->SetReactState(REACT_AGGRESSIVE);
                         me->SetInCombatWithZone();
                         break;
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_twin_valkyr.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_twin_valkyr.cpp
index 73dd987171e..49bd28f7e56 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_twin_valkyr.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/boss_twin_valkyr.cpp
@@ -203,7 +203,8 @@ struct boss_twin_baseAI : public BossAI
         switch (uiId)
         {
             case 1:
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(false);
                 me->SetReactState(REACT_AGGRESSIVE);
                 break;
             default:
diff --git a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/trial_of_the_crusader.cpp b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/trial_of_the_crusader.cpp
index 8a404f66cc5..fdc93f56c39 100644
--- a/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/trial_of_the_crusader.cpp
+++ b/src/server/scripts/Northrend/CrusadersColiseum/TrialOfTheCrusader/trial_of_the_crusader.cpp
@@ -241,7 +241,8 @@ class npc_announcer_toc10 : public CreatureScript
                     if (Creature* jaraxxus = ObjectAccessor::GetCreature(*player, instance->GetGuidData(NPC_JARAXXUS)))
                     {
                         jaraxxus->RemoveAurasDueToSpell(SPELL_JARAXXUS_CHAINS);
-                        jaraxxus->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        jaraxxus->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                        jaraxxus->SetImmuneToPC(false);
                         jaraxxus->SetReactState(REACT_DEFENSIVE);
                         jaraxxus->SetInCombatWithZone();
                     }
@@ -430,7 +431,8 @@ class npc_fizzlebang_toc : public CreatureScript
                 _instance->SetData(TYPE_EVENT, 1180);
                 if (Creature* jaraxxus = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(NPC_JARAXXUS)))
                 {
-                    jaraxxus->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                    jaraxxus->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                    jaraxxus->SetImmuneToPC(false);
                     jaraxxus->SetReactState(REACT_AGGRESSIVE);
                     jaraxxus->SetInCombatWithZone();
                 }
@@ -527,7 +529,8 @@ class npc_fizzlebang_toc : public CreatureScript
                             Talk(SAY_STAGE_1_04);
                             if (Creature* jaraxxus = me->SummonCreature(NPC_JARAXXUS, ToCCommonLoc[1].GetPositionX(), ToCCommonLoc[1].GetPositionY(), ToCCommonLoc[1].GetPositionZ(), 5.0f, TEMPSUMMON_CORPSE_TIMED_DESPAWN, DESPAWN_TIME))
                             {
-                                jaraxxus->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                                jaraxxus->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                                jaraxxus->SetImmuneToPC(true);
                                 jaraxxus->SetReactState(REACT_PASSIVE);
                                 jaraxxus->GetMotionMaster()->MovePoint(0, ToCCommonLoc[1].GetPositionX(), ToCCommonLoc[1].GetPositionY()-10, ToCCommonLoc[1].GetPositionZ());
                             }
diff --git a/src/server/scripts/Northrend/DraktharonKeep/boss_trollgore.cpp b/src/server/scripts/Northrend/DraktharonKeep/boss_trollgore.cpp
index fd8b209e0cb..a70bf5992e8 100644
--- a/src/server/scripts/Northrend/DraktharonKeep/boss_trollgore.cpp
+++ b/src/server/scripts/Northrend/DraktharonKeep/boss_trollgore.cpp
@@ -213,7 +213,7 @@ class npc_drakkari_invader : public CreatureScript
                 if (type == POINT_MOTION_TYPE && pointId == POINT_LANDING)
                 {
                     me->Dismount();
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                    me->SetImmuneToAll(false);
                     DoCastAOE(SPELL_INVADER_TAUNT);
                 }
             }
diff --git a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/boss_horAI.cpp b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/boss_horAI.cpp
index 4aec3a9ed78..9da3da05f95 100644
--- a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/boss_horAI.cpp
+++ b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/boss_horAI.cpp
@@ -27,7 +27,7 @@ void boss_horAI::Reset()
 {
     _Reset();
     me->SetVisible(false);
-    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+    me->SetImmuneToAll(true);
     me->SetReactState(REACT_PASSIVE);
     if (instance->GetData(DATA_WAVE_COUNT) != NOT_STARTED)
         instance->ProcessEvent(nullptr, EVENT_DO_WIPE);
@@ -38,7 +38,7 @@ void boss_horAI::DoAction(int32 actionId)
     switch (actionId)
     {
         case ACTION_ENTER_COMBAT: // called by InstanceScript when boss shall enter in combat.
-            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+            me->SetImmuneToAll(false);
             me->SetReactState(REACT_AGGRESSIVE);
             DoZoneInCombat(me, 150.0f);
             break;
diff --git a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/halls_of_reflection.cpp b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/halls_of_reflection.cpp
index 326a78c03c4..7d620ae5a60 100644
--- a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/halls_of_reflection.cpp
+++ b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/halls_of_reflection.cpp
@@ -1032,7 +1032,7 @@ class npc_jaina_or_sylvanas_escape_hor : public CreatureScript
 
                             if (Creature* lichking = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_THE_LICH_KING_ESCAPE)))
                             {
-                                lichking->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                                lichking->SetImmuneToPC(true);
                                 lichking->RemoveAllAttackers();
 
                                 DeleteAllFromThreatList(lichking, me->GetGUID());
@@ -1046,7 +1046,8 @@ class npc_jaina_or_sylvanas_escape_hor : public CreatureScript
                         case EVENT_ESCAPE_6:
                             if (Creature* lichking = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_THE_LICH_KING_ESCAPE)))
                             {
-                                lichking->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_PACIFIED);
+                                lichking->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_PACIFIED);
+                                lichking->SetImmuneToPC(false);
 
                                 if (_instance->GetData(DATA_TEAM_IN_INSTANCE) == ALLIANCE)
                                 {
@@ -1929,7 +1930,7 @@ class npc_frostsworn_general : public CreatureScript
                 {
                     if (Creature* reflection = me->SummonCreature(NPC_REFLECTION, *target, TEMPSUMMON_TIMED_DESPAWN_OUT_OF_COMBAT, 3000))
                     {
-                        reflection->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        reflection->SetImmuneToPC(false);
                         target->CastSpell(reflection, SPELL_CLONE, true);
                         target->CastSpell(reflection, SPELL_GHOST_VISUAL, true);
                         reflection->AI()->AttackStart(target);
@@ -2164,7 +2165,7 @@ struct npc_escape_event_trash : public ScriptedAI
         DoZoneInCombat(me, 0.0f);
         if (Creature* leader = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_ESCAPE_LEADER)))
         {
-            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetImmuneToPC(false);
             me->SetInCombatWith(leader);
             leader->SetInCombatWith(me);
             AddThreat(leader, 0.0f);
@@ -2595,7 +2596,7 @@ class npc_quel_delar_sword : public CreatureScript
                 if (_intro)
                     _events.ScheduleEvent(EVENT_QUEL_DELAR_INIT, 0);
                 else
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                    me->SetImmuneToAll(false);
             }
 
             void EnterCombat(Unit* /*victim*/) override
@@ -2663,7 +2664,7 @@ class npc_quel_delar_sword : public CreatureScript
                             case EVENT_QUEL_DELAR_FIGHT:
                                 Talk(SAY_QUEL_DELAR_SWORD);
                                 me->GetMotionMaster()->MovePoint(0, QuelDelarMovement[2]);
-                                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                me->SetImmuneToAll(false);
                                 break;
                             default:
                                 break;
diff --git a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/instance_halls_of_reflection.cpp b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/instance_halls_of_reflection.cpp
index 936a1117b88..89f95a32cc8 100644
--- a/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/instance_halls_of_reflection.cpp
+++ b/src/server/scripts/Northrend/FrozenHalls/HallsOfReflection/instance_halls_of_reflection.cpp
@@ -590,7 +590,8 @@ class instance_halls_of_reflection : public InstanceMapScript
                                 if (Creature* temp = instance->GetCreature(guid))
                                 {
                                     temp->CastSpell(temp, SPELL_SPIRIT_ACTIVATE, false);
-                                    temp->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC | UNIT_FLAG_NOT_SELECTABLE);
+                                    temp->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                                    temp->SetImmuneToAll(false);
                                     temp->AI()->DoZoneInCombat(temp, 100.00f);
                                 }
                             }
diff --git a/src/server/scripts/Northrend/Gundrak/boss_drakkari_colossus.cpp b/src/server/scripts/Northrend/Gundrak/boss_drakkari_colossus.cpp
index 465bb9bcf24..110341a552f 100644
--- a/src/server/scripts/Northrend/Gundrak/boss_drakkari_colossus.cpp
+++ b/src/server/scripts/Northrend/Gundrak/boss_drakkari_colossus.cpp
@@ -108,7 +108,7 @@ class boss_drakkari_colossus : public CreatureScript
                 if (GetData(DATA_INTRO_DONE))
                 {
                     me->SetReactState(REACT_AGGRESSIVE);
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(false);
                     me->RemoveAura(SPELL_FREEZE_ANIM);
                 }
 
@@ -140,7 +140,7 @@ class boss_drakkari_colossus : public CreatureScript
                         me->GetMotionMaster()->MoveIdle();
 
                         me->SetReactState(REACT_PASSIVE);
-                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        me->SetImmuneToPC(true);
                         DoCast(me, SPELL_FREEZE_ANIM);
                         break;
                     case ACTION_UNFREEZE_COLOSSUS:
@@ -149,7 +149,7 @@ class boss_drakkari_colossus : public CreatureScript
                             return;
 
                         me->SetReactState(REACT_AGGRESSIVE);
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        me->SetImmuneToPC(false);
                         me->RemoveAura(SPELL_FREEZE_ANIM);
 
                         me->SetInCombatWithZone();
@@ -163,7 +163,7 @@ class boss_drakkari_colossus : public CreatureScript
 
             void DamageTaken(Unit* /*attacker*/, uint32& damage) override
             {
-                if (me->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC))
+                if (me->IsImmuneToPC())
                     damage = 0;
 
                 if (phase == COLOSSUS_PHASE_NORMAL ||
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_prince_council.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_prince_council.cpp
index 28be5f8ccc0..f038f653782 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_prince_council.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_prince_council.cpp
@@ -244,7 +244,8 @@ class boss_blood_council_controller : public CreatureScript
                     for (uint32 bossData : PrincesData)
                         if (Creature* prince = ObjectAccessor::GetCreature(*me, instance->GetGuidData(bossData)))
                         {
-                            prince->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                            prince->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                            prince->SetImmuneToPC(false);
                             if (bossData == DATA_PRINCE_VALANAR)
                                 prince->SetHealth(prince->GetMaxHealth());
                         }
@@ -453,7 +454,7 @@ struct BloodPrincesBossAI : public BossAI
         summons.DespawnAll();
         me->SetCombatPulseDelay(0);
 
-        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+        me->SetImmuneToPC(false);
         _isEmpowered = false;
         me->SetHealth(_spawnHealth);
         instance->SetData(DATA_ORB_WHISPERER_ACHIEVEMENT, uint32(true));
@@ -562,7 +563,8 @@ struct BloodPrincesBossAI : public BossAI
         {
             case ACTION_STAND_UP:
                 me->RemoveAurasDueToSpell(SPELL_FEIGN_DEATH);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(false);
                 me->RemoveFlag(UNIT_DYNAMIC_FLAGS, UNIT_DYNFLAG_DEAD);
                 me->RemoveFlag(UNIT_FIELD_FLAGS_2, UNIT_FLAG2_FEIGN_DEATH);
                 me->ForceValuesUpdateAtIndex(UNIT_NPC_FLAGS);   // was in sniff. don't ask why
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_deathbringer_saurfang.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_deathbringer_saurfang.cpp
index f5568b4c298..e2951277101 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_deathbringer_saurfang.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_deathbringer_saurfang.cpp
@@ -295,7 +295,7 @@ class boss_deathbringer_saurfang : public CreatureScript
 
                 events.Reset();
                 events.SetPhase(PHASE_COMBAT);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(false);
                 if (!_introDone)
                 {
                     DoCast(me, SPELL_GRIP_OF_AGONY);
@@ -323,7 +323,7 @@ class boss_deathbringer_saurfang : public CreatureScript
 
             void AttackStart(Unit* victim) override
             {
-                if (me->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC))
+                if (me->IsImmuneToPC())
                     return;
 
                 ScriptedAI::AttackStart(victim);
@@ -333,7 +333,7 @@ class boss_deathbringer_saurfang : public CreatureScript
             {
                 ScriptedAI::EnterEvadeMode(why);
                 if (_introDone)
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(false);
             }
 
             void JustReachedHome() override
@@ -369,7 +369,8 @@ class boss_deathbringer_saurfang : public CreatureScript
                     _dead = true;
                     _JustDied();
                     _EnterEvadeMode();
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(true);
 
                     DoCastAOE(SPELL_REMOVE_MARKS_OF_THE_FALLEN_CHAMPION);
                     DoCast(me, SPELL_ACHIEVEMENT, true);
@@ -489,7 +490,7 @@ class boss_deathbringer_saurfang : public CreatureScript
                         case EVENT_INTRO_FINISH:
                             events.SetPhase(PHASE_COMBAT);
                             _introDone = true;
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                            me->SetImmuneToPC(false);
                             break;
                         case EVENT_SUMMON_BLOOD_BEAST:
                             for (uint32 i10 = 0; i10 < 2; ++i10)
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
index ce92ffc6abc..b23b3ca9917 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
@@ -249,7 +249,10 @@ class boss_professor_putricide : public CreatureScript
                     me->GetMotionMaster()->MovementExpired();
 
                 if (instance->GetBossState(DATA_ROTFACE) == DONE && instance->GetBossState(DATA_FESTERGUT) == DONE)
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                {
+                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(false);
+                }
             }
 
             void EnterCombat(Unit* who) override
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_sindragosa.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_sindragosa.cpp
index 4bf8f97f623..81e092f57a2 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_sindragosa.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_sindragosa.cpp
@@ -849,7 +849,7 @@ class npc_rimefang : public CreatureScript
 
                     me->setActive(true);
                     me->SetSpeedRate(MOVE_FLIGHT, 2.0f);
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(true);
                     float moveTime = me->GetExactDist(&RimefangFlyPos) / (me->GetSpeed(MOVE_FLIGHT) * 0.001f);
                     me->m_Events.AddEvent(new FrostwyrmLandEvent(*me, RimefangLandPos), me->m_Events.CalculateTime(uint64(moveTime) + 250));
                     me->SetDefaultMovementType(IDLE_MOTION_TYPE);
@@ -871,7 +871,7 @@ class npc_rimefang : public CreatureScript
                 me->RemoveByteFlag(UNIT_FIELD_BYTES_1, UNIT_BYTES_1_OFFSET_ANIM_TIER, UNIT_BYTE1_FLAG_ALWAYS_STAND | UNIT_BYTE1_FLAG_HOVER);
                 me->SetHomePosition(RimefangLandPos);
                 me->SetFacingTo(RimefangLandPos.GetOrientation());
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(false);
                 me->SetReactState(REACT_AGGRESSIVE);
             }
 
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_the_lich_king.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_the_lich_king.cpp
index 97b3261f51e..d00e56606b5 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_the_lich_king.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_the_lich_king.cpp
@@ -527,7 +527,7 @@ class boss_the_lich_king : public CreatureScript
             void Reset() override
             {
                 _Reset();
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(true);
                 me->SetReactState(REACT_PASSIVE);
                 events.SetPhase(PHASE_INTRO);
                 Initialize();
@@ -936,7 +936,7 @@ class boss_the_lich_king : public CreatureScript
                             break;
                         case EVENT_FINISH_INTRO:
                             me->SetWalk(false);
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                            me->SetImmuneToPC(false);
                             me->SetReactState(REACT_AGGRESSIVE);
                             events.SetPhase(PHASE_ONE);
                             DoZoneInCombat();
@@ -1855,7 +1855,7 @@ class npc_terenas_menethil : public CreatureScript
                             if (Creature* lichKing = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_THE_LICH_KING)))
                             {
                                 lichKing->AI()->DoAction(ACTION_FINISH_OUTRO);
-                                lichKing->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_NPC);
+                                lichKing->SetImmuneToNPC(false);
                                 if (Creature* tirion = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_HIGHLORD_TIRION_FORDRING)))
                                     tirion->AI()->AttackStart(lichKing);
                             }
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp b/src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp
index 2ddfa86f5fa..ed85ee3fa17 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp
@@ -837,7 +837,7 @@ class boss_sister_svalna : public CreatureScript
                     case ACTION_START_GAUNTLET:
                         me->setActive(true);
                         _isEventInProgress = true;
-                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                        me->SetImmuneToAll(true);
                         events.ScheduleEvent(EVENT_SVALNA_START, 25000);
                         break;
                     case ACTION_RESURRECT_CAPTAINS:
@@ -871,7 +871,7 @@ class boss_sister_svalna : public CreatureScript
 
                 _isEventInProgress = false;
                 me->setActive(false);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                me->SetImmuneToAll(false);
                 me->SetDisableGravity(false);
                 me->SetHover(false);
             }
@@ -1042,7 +1042,7 @@ class npc_crok_scourgebane : public CreatureScript
                 {
                     // pause pathing until trash pack is cleared
                     case 0:
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_NPC);
+                        me->SetImmuneToNPC(false);
                         Talk(SAY_CROK_COMBAT_WP_0);
                         if (!_aliveTrash.empty())
                             SetEscortPaused(true);
@@ -1788,7 +1788,8 @@ class spell_icc_stoneform : public SpellScriptLoader
                 if (Creature* target = GetTarget()->ToCreature())
                 {
                     target->SetReactState(REACT_PASSIVE);
-                    target->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                    target->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    target->SetImmuneToPC(true);
                     target->SetUInt32Value(UNIT_NPC_EMOTESTATE, EMOTE_STATE_CUSTOM_SPELL_02);
                 }
             }
@@ -1798,7 +1799,8 @@ class spell_icc_stoneform : public SpellScriptLoader
                 if (Creature* target = GetTarget()->ToCreature())
                 {
                     target->SetReactState(REACT_AGGRESSIVE);
-                    target->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                    target->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    target->SetImmuneToPC(false);
                     target->SetUInt32Value(UNIT_NPC_EMOTESTATE, 0);
                 }
             }
diff --git a/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp b/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
index faaafac710a..02313e8d286 100644
--- a/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
+++ b/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
@@ -224,7 +224,8 @@ public:
                     return;
                 _Reset();
                 me->SetReactState(REACT_PASSIVE);
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(true);
                 _skeletonCount = 0;
                 _bansheeCount = 0;
                 _abominationCount = 0;
@@ -424,7 +425,8 @@ public:
                         case EVENT_PHASE_TWO:
                             me->CastStop();
                             events.SetPhase(PHASE_TWO);
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                            me->SetImmuneToPC(false);
                             ResetThreatList();
                             me->SetReactState(REACT_AGGRESSIVE);
                             Talk(EMOTE_PHASE_TWO);
@@ -521,7 +523,7 @@ public:
                     case ACTION_BEGIN_ENCOUNTER:
                         if (instance->GetBossState(BOSS_KELTHUZAD) != NOT_STARTED)
                             return;
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        me->SetImmuneToPC(false);
                         instance->SetBossState(BOSS_KELTHUZAD, IN_PROGRESS);
                         events.SetPhase(PHASE_ONE);
                         DoZoneInCombat();
@@ -805,7 +807,7 @@ public:
                         me->RemoveAllAuras();
                         me->CombatStop();
                         me->StopMoving();
-                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        me->SetImmuneToPC(true);
                         me->DespawnOrUnsummon(30 * IN_MILLISECONDS); // just in case anything interrupts the movement
                         me->GetMotionMaster()->MoveTargetedHome();
                     default:
diff --git a/src/server/scripts/Northrend/Naxxramas/boss_noth.cpp b/src/server/scripts/Northrend/Naxxramas/boss_noth.cpp
index b7333e90e2e..840a8c0dba7 100644
--- a/src/server/scripts/Northrend/Naxxramas/boss_noth.cpp
+++ b/src/server/scripts/Northrend/Naxxramas/boss_noth.cpp
@@ -105,7 +105,8 @@ public:
             {
                 DoCastAOE(SPELL_TELEPORT_BACK);
                 me->SetReactState(REACT_AGGRESSIVE);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(false);
             }
 
             balconyCount = 0;
@@ -243,7 +244,8 @@ public:
                     case EVENT_BALCONY:
                         events.SetPhase(PHASE_BALCONY);
                         me->SetReactState(REACT_PASSIVE);
-                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(true, true);
                         me->AttackStop();
                         me->StopMoving();
                         me->RemoveAllAuras();
@@ -299,7 +301,8 @@ public:
                         EnterPhaseGround();
                         break;
                     case EVENT_GROUND_ATTACKABLE:
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->SetReactState(REACT_AGGRESSIVE);
                         break;
                 }
diff --git a/src/server/scripts/Northrend/Naxxramas/boss_thaddius.cpp b/src/server/scripts/Northrend/Naxxramas/boss_thaddius.cpp
index d6a36680c33..5233a49b881 100644
--- a/src/server/scripts/Northrend/Naxxramas/boss_thaddius.cpp
+++ b/src/server/scripts/Northrend/Naxxramas/boss_thaddius.cpp
@@ -330,7 +330,8 @@ public:
                 me->DespawnOrUnsummon();
                 me->SetRespawnTime(initial ? 5 : 30);
 
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_STUNNED);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_STUNNED);
+                me->SetImmuneToPC(true);
                 events.SetPhase(PHASE_RESETTING);
                 if (Creature* feugen = ObjectAccessor::GetCreature(*me, instance->GetGuidData(DATA_FEUGEN)))
                     feugen->AI()->DoAction(ACTION_BEGIN_RESET_ENCOUNTER);
@@ -395,7 +396,7 @@ public:
                             ballLightningUnlocked = false;
                             me->RemoveAura(SPELL_THADDIUS_INACTIVE_VISUAL);
                             me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_STUNNED);
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                            me->SetImmuneToPC(false);
                             me->SetReactState(REACT_AGGRESSIVE);
 
                             DoZoneInCombat();
@@ -652,7 +653,7 @@ public:
                     if (!isOverloading)
                     {
                         isOverloading = true;
-                        caster->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        caster->SetImmuneToPC(false);
                         if (Creature* creatureCaster = caster->ToCreature())
                             creatureCaster->AI()->Talk(EMOTE_TESLA_LINK_BREAKS);
                         me->RemoveAura(SPELL_STALAGG_CHAIN_VISUAL);
@@ -669,7 +670,7 @@ public:
                     refreshBeam = false;
                     caster->CastStop();
                     caster->CastSpell(me, SPELL_STALAGG_CHAIN_VISUAL, true);
-                    caster->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    caster->SetImmuneToPC(true);
                 }
             }
 
@@ -919,7 +920,7 @@ public:
                     if (!isOverloading)
                     {
                         isOverloading = true;
-                        caster->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        caster->SetImmuneToPC(false);
                         if (Creature* creatureCaster = caster->ToCreature())
                             creatureCaster->AI()->Talk(EMOTE_TESLA_LINK_BREAKS);
                         me->RemoveAura(SPELL_STALAGG_CHAIN_VISUAL);
@@ -936,7 +937,7 @@ public:
                     refreshBeam = false;
                     caster->CastStop();
                     caster->CastSpell(me, SPELL_FEUGEN_CHAIN_VISUAL, true);
-                    caster->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    caster->SetImmuneToPC(true);
                 }
             }
 
diff --git a/src/server/scripts/Northrend/Nexus/EyeOfEternity/boss_malygos.cpp b/src/server/scripts/Northrend/Nexus/EyeOfEternity/boss_malygos.cpp
index 553300715e5..8e51d79a87b 100644
--- a/src/server/scripts/Northrend/Nexus/EyeOfEternity/boss_malygos.cpp
+++ b/src/server/scripts/Northrend/Nexus/EyeOfEternity/boss_malygos.cpp
@@ -376,7 +376,7 @@ public:
 
             me->SetDisableGravity(true);
             me->SetByteFlag(UNIT_FIELD_BYTES_1, UNIT_BYTES_1_OFFSET_ANIM_TIER, UNIT_BYTE1_FLAG_ALWAYS_STAND | UNIT_BYTE1_FLAG_HOVER);
-            me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+            me->SetImmuneToAll(true);
             me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
             // TO DO: find what in core is making boss slower than in retail (when correct speed data) or find missing movement flag update or forced spline change
             me->SetSpeedRate(MOVE_FLIGHT, _flySpeed * 0.25f);
@@ -466,7 +466,7 @@ public:
                         pos.m_positionZ = alexstraszaBunny->GetPositionZ();
                         alexstraszaBunny->GetNearPoint2D(pos.m_positionX, pos.m_positionY, 30.0f, alexstraszaBunny->GetAngle(me));
                         me->GetMotionMaster()->MoveLand(POINT_LAND_P_ONE, pos);
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                        me->SetImmuneToAll(false);
                         me->SetReactState(REACT_AGGRESSIVE);
                         me->SetInCombatWithZone();
                         events.ScheduleEvent(EVENT_LAND_START_ENCOUNTER, 7*IN_MILLISECONDS, 1, PHASE_NOT_STARTED);
diff --git a/src/server/scripts/Northrend/Nexus/Nexus/boss_keristrasza.cpp b/src/server/scripts/Northrend/Nexus/Nexus/boss_keristrasza.cpp
index cb17a64563a..0de036eb782 100644
--- a/src/server/scripts/Northrend/Nexus/Nexus/boss_keristrasza.cpp
+++ b/src/server/scripts/Northrend/Nexus/Nexus/boss_keristrasza.cpp
@@ -138,14 +138,14 @@ class boss_keristrasza : public CreatureScript
             {
                 if (remove)
                 {
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(false);
                     me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
                     if (me->HasAura(SPELL_FROZEN_PRISON))
                         me->RemoveAurasDueToSpell(SPELL_FROZEN_PRISON);
                 }
                 else
                 {
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(true);
                     me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
                     DoCast(me, SPELL_FROZEN_PRISON, false);
                 }
diff --git a/src/server/scripts/Northrend/Nexus/Oculus/boss_varos.cpp b/src/server/scripts/Northrend/Nexus/Oculus/boss_varos.cpp
index 460288d99f0..8b18640c6cd 100644
--- a/src/server/scripts/Northrend/Nexus/Oculus/boss_varos.cpp
+++ b/src/server/scripts/Northrend/Nexus/Oculus/boss_varos.cpp
@@ -285,7 +285,8 @@ class spell_varos_centrifuge_shield : public SpellScriptLoader
                     if (caster->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_UNK_15|UNIT_FLAG_IMMUNE_TO_NPC|UNIT_FLAG_IMMUNE_TO_PC|UNIT_FLAG_UNK_6))
                     {
                         caster->ToCreature()->SetReactState(REACT_PASSIVE);
-                        caster->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_UNK_15|UNIT_FLAG_IMMUNE_TO_NPC|UNIT_FLAG_IMMUNE_TO_PC|UNIT_FLAG_UNK_6);
+                        caster->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_UNK_15|UNIT_FLAG_UNK_6);
+                        caster->SetImmuneToAll(true, true);
                     }
                 }
             }
@@ -295,7 +296,8 @@ class spell_varos_centrifuge_shield : public SpellScriptLoader
                 if (Unit* caster = GetCaster())
                 {
                     caster->ToCreature()->SetReactState(REACT_AGGRESSIVE);
-                    caster->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_UNK_15|UNIT_FLAG_IMMUNE_TO_NPC|UNIT_FLAG_IMMUNE_TO_PC|UNIT_FLAG_UNK_6);
+                    caster->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_UNK_15|UNIT_FLAG_UNK_6);
+                    caster->SetImmuneToAll(false);
                 }
             }
 
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_algalon_the_observer.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_algalon_the_observer.cpp
index 72a911d398e..69d5fa4d2fb 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_algalon_the_observer.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_algalon_the_observer.cpp
@@ -379,11 +379,12 @@ class boss_algalon_the_observer : public CreatureScript
                         events.ScheduleEvent(EVENT_DESPAWN_ALGALON_2, 17000);
                         events.ScheduleEvent(EVENT_DESPAWN_ALGALON_3, 26000);
                         me->DespawnOrUnsummon(34000);
-                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_NPC);
+                        me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToNPC(true);
                         break;
                     case ACTION_INIT_ALGALON:
                         _firstPull = false;
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        me->SetImmuneToPC(false);
                         break;
                 }
             }
@@ -396,7 +397,8 @@ class boss_algalon_the_observer : public CreatureScript
             void EnterCombat(Unit* /*target*/) override
             {
                 uint32 introDelay = 0;
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_NPC);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToNPC(true);
                 events.Reset();
                 events.SetPhase(PHASE_ROLE_PLAY);
 
@@ -503,7 +505,7 @@ class boss_algalon_the_observer : public CreatureScript
             {
                 instance->SetBossState(BOSS_ALGALON, FAIL);
                 BossAI::EnterEvadeMode(why);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(false);
                 me->SetSheath(SHEATH_STATE_UNARMED);
             }
 
@@ -578,7 +580,7 @@ class boss_algalon_the_observer : public CreatureScript
                             break;
                         case EVENT_INTRO_FINISH:
                             events.Reset();
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                            me->SetImmuneToPC(false);
                             break;
                         case EVENT_START_COMBAT:
                             instance->SetBossState(BOSS_ALGALON, IN_PROGRESS);
@@ -587,7 +589,8 @@ class boss_algalon_the_observer : public CreatureScript
                         {
                             events.SetPhase(PHASE_NORMAL);
                             me->SetSheath(SHEATH_STATE_MELEE);
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_NPC);
+                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                            me->SetImmuneToNPC(false);
                             me->SetReactState(REACT_DEFENSIVE);
                             DoCastAOE(SPELL_SUPERMASSIVE_FAIL, true);
                             //! Workaround for Creature::_IsTargetAcceptable returning false
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_freya.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_freya.cpp
index b436f196b40..2a018700b34 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_freya.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_freya.cpp
@@ -1356,7 +1356,8 @@ class npc_healthy_spore : public CreatureScript
             npc_healthy_sporeAI(Creature* creature) : ScriptedAI(creature)
             {
                 SetCombatMovement(false);
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_NON_ATTACKABLE);
+                me->SetImmuneToPC(true);
                 me->SetReactState(REACT_PASSIVE);
                 DoCast(me, SPELL_HEALTHY_SPORE_VISUAL);
                 DoCast(me, SPELL_POTENT_PHEROMONES);
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_ignis.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_ignis.cpp
index 1fb7dda696a..ae61452dc6e 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_ignis.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_ignis.cpp
@@ -181,7 +181,8 @@ class boss_ignis : public CreatureScript
                 {
                     summon->SetFaction(FACTION_MONSTER_2);
                     summon->SetReactState(REACT_AGGRESSIVE);
-                    summon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_PACIFIED | UNIT_FLAG_STUNNED | UNIT_FLAG_IMMUNE_TO_PC);
+                    summon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_PACIFIED | UNIT_FLAG_STUNNED);
+                    summon->SetImmuneToPC(false);
                     summon->SetControlled(false, UNIT_STATE_ROOT);
                 }
 
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_mimiron.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_mimiron.cpp
index 4859e376779..3b95b36c375 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_mimiron.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_mimiron.cpp
@@ -981,7 +981,8 @@ class boss_vx_001 : public CreatureScript
                         events.ScheduleEvent(EVENT_FLAME_SUPPRESSANT_VX, 6000);
                         // Missing break intended.
                     case DO_START_VX001:
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->RemoveAurasDueToSpell(SPELL_FREEZE_ANIM);
                         me->SetUInt32Value(UNIT_NPC_EMOTESTATE, EMOTE_ONESHOT_NONE); // Remove emotestate.
                         //me->SetUInt32Value(UNIT_FIELD_BYTES_1, UNIT_BYTES_1_OFFSET_ANIM_TIER, UNIT_BYTE1_FLAG_ALWAYS_STAND | UNIT_BYTE1_FLAG_HOVER); Blizzard handles hover animation like this it seems.
@@ -1157,7 +1158,8 @@ class boss_aerial_command_unit : public CreatureScript
                         events.ScheduleEvent(EVENT_SUMMON_FIRE_BOTS, 1000, 0, PHASE_AERIAL_COMMAND_UNIT);
                         // Missing break intended.
                     case DO_START_AERIAL:
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                        me->SetImmuneToPC(false);
                         me->SetReactState(REACT_AGGRESSIVE);
 
                         events.SetPhase(PHASE_AERIAL_COMMAND_UNIT);
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_thorim.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_thorim.cpp
index 118c293755a..9c6cffcba13 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_thorim.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_thorim.cpp
@@ -474,7 +474,7 @@ class boss_thorim : public CreatureScript
                 me->SetReactState(REACT_PASSIVE);
                 me->SetDisableGravity(true);
                 me->SetControlled(true, UNIT_STATE_ROOT);
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(true);
 
                 events.SetPhase(PHASE_NULL);
 
@@ -631,7 +631,7 @@ class boss_thorim : public CreatureScript
 
                 if (Creature* runicColossus = instance->GetCreature(DATA_RUNIC_COLOSSUS))
                 {
-                    runicColossus->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    runicColossus->SetImmuneToPC(false);
                     runicColossus->AI()->DoAction(ACTION_ACTIVATE_ADDS);
                 }
 
@@ -838,7 +838,7 @@ class boss_thorim : public CreatureScript
                         if (++_killedCount >= 6)
                         {
                             // Event starts
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                            me->SetImmuneToPC(false);
                             DoZoneInCombat(me);
                         }
                         break;
@@ -1356,7 +1356,7 @@ struct npc_thorim_minibossAI : public ScriptedAI
         {
             for (ObjectGuid const& guid : _summons)
                 if (Creature* summon = ObjectAccessor::GetCreature(*me, guid))
-                    summon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    summon->SetImmuneToPC(false);
         }
     }
 
@@ -1426,7 +1426,7 @@ class npc_runic_colossus : public CreatureScript
 
                 if (Creature* giant = _instance->GetCreature(DATA_RUNE_GIANT))
                 {
-                    giant->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    giant->SetImmuneToPC(false);
                     giant->AI()->DoAction(ACTION_ACTIVATE_ADDS);
                 }
             }
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_yogg_saron.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_yogg_saron.cpp
index 7f3a2120e88..c3817b0525b 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/boss_yogg_saron.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/boss_yogg_saron.cpp
@@ -1048,7 +1048,8 @@ class boss_brain_of_yogg_saron : public CreatureScript
 
             void Reset() override
             {
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(false);
                 DoCast(me, SPELL_MATCH_HEALTH);
                 _summons.DespawnAll();
             }
@@ -1062,7 +1063,8 @@ class boss_brain_of_yogg_saron : public CreatureScript
                     DoCastAOE(SPELL_SHATTERED_ILLUSION_REMOVE, true);
                     DoCast(me, SPELL_MATCH_HEALTH_2, true); // it doesn't seem to hit Yogg-Saron here
                     DoCast(me, SPELL_BRAIN_HURT_VISUAL, true);
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(true);
 
                     if (Creature* voice = _instance->GetCreature(DATA_VOICE_OF_YOGG_SARON))
                         voice->AI()->DoAction(ACTION_PHASE_THREE);
diff --git a/src/server/scripts/Northrend/Ulduar/Ulduar/instance_ulduar.cpp b/src/server/scripts/Northrend/Ulduar/Ulduar/instance_ulduar.cpp
index e023be23cd4..bd1d2b9c3b6 100644
--- a/src/server/scripts/Northrend/Ulduar/Ulduar/instance_ulduar.cpp
+++ b/src/server/scripts/Northrend/Ulduar/Ulduar/instance_ulduar.cpp
@@ -228,7 +228,7 @@ class instance_ulduar : public InstanceMapScript
                     if (_algalonTimer && _algalonTimer <= 60)
                         algalon->AI()->DoAction(ACTION_INIT_ALGALON);
                     else
-                        algalon->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                        algalon->SetImmuneToPC(false);
                 }
 
                 // Keepers at Observation Ring
diff --git a/src/server/scripts/Northrend/UtgardeKeep/UtgardeKeep/boss_ingvar_the_plunderer.cpp b/src/server/scripts/Northrend/UtgardeKeep/UtgardeKeep/boss_ingvar_the_plunderer.cpp
index 3d2fa75ecac..743adbb739f 100644
--- a/src/server/scripts/Northrend/UtgardeKeep/UtgardeKeep/boss_ingvar_the_plunderer.cpp
+++ b/src/server/scripts/Northrend/UtgardeKeep/UtgardeKeep/boss_ingvar_the_plunderer.cpp
@@ -113,7 +113,8 @@ class boss_ingvar_the_plunderer : public CreatureScript
             {
                 if (me->GetEntry() != NPC_INGVAR)
                     me->UpdateEntry(NPC_INGVAR);
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                me->SetImmuneToPC(false);
 
                 _Reset();
             }
@@ -129,7 +130,8 @@ class boss_ingvar_the_plunderer : public CreatureScript
                     me->StopMoving();
                     DoCast(me, SPELL_INGVAR_FEIGN_DEATH, true);
 
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(true, true);
 
                     Talk(SAY_DEATH);
                 }
@@ -227,7 +229,8 @@ class boss_ingvar_the_plunderer : public CreatureScript
                             break;
                         case EVENT_JUST_TRANSFORMED:
                             ScheduleSecondPhase();
-                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_NOT_SELECTABLE);
+                            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
+                            me->SetImmuneToPC(false);
                             if (Unit* target = me->GetThreatManager().SelectVictim())
                                 AttackStart(target);
                             else
diff --git a/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_palehoof.cpp b/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_palehoof.cpp
index 60426fe448f..4d0dcd4cd74 100644
--- a/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_palehoof.cpp
+++ b/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_palehoof.cpp
@@ -292,7 +292,7 @@ public:
                 }
                 case ACTION_START_FIGHT:
                     me->RemoveAurasDueToSpell(SPELL_FREEZE);
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(false);
                     DoZoneInCombat();
                     if (Creature* orb = ObjectAccessor::GetCreature(*me, _orb))
                         orb->DespawnOrUnsummon(1000);
@@ -345,7 +345,7 @@ struct PalehoofMinionsBossAI : public BossAI
         if (actionId == ACTION_START_FIGHT)
         {
             me->RemoveAurasDueToSpell(SPELL_FREEZE);
-            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+            me->SetImmuneToPC(false);
             DoZoneInCombat();
         }
     }
diff --git a/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_skadi.cpp b/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_skadi.cpp
index effd1741bf1..968210df209 100644
--- a/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_skadi.cpp
+++ b/src/server/scripts/Northrend/UtgardeKeep/UtgardePinnacle/boss_skadi.cpp
@@ -265,7 +265,8 @@ public:
                     Talk(SAY_DRAKE_DEATH);
                     DoCast(me, SPELL_SKADI_TELEPORT, true);
                     summons.DespawnEntry(NPC_WORLD_TRIGGER);
-                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                    me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(false);
                     me->SetReactState(REACT_AGGRESSIVE);
                     _phase = PHASE_GROUND;
 
diff --git a/src/server/scripts/Northrend/VioletHold/instance_violet_hold.cpp b/src/server/scripts/Northrend/VioletHold/instance_violet_hold.cpp
index cf5d256f3a6..b2c37cc59b6 100644
--- a/src/server/scripts/Northrend/VioletHold/instance_violet_hold.cpp
+++ b/src/server/scripts/Northrend/VioletHold/instance_violet_hold.cpp
@@ -557,7 +557,7 @@ class instance_violet_hold : public InstanceMapScript
                                 {
                                     if (Creature* moragg = GetCreature(DATA_MORAGG))
                                     {
-                                        moragg->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                        moragg->SetImmuneToAll(false);
                                         moragg->AI()->DoZoneInCombat(moragg, 200.0f);
                                     }
                                 });
@@ -590,12 +590,12 @@ class instance_violet_hold : public InstanceMapScript
                                         for (uint32 i = DATA_EREKEM_GUARD_1; i <= DATA_EREKEM_GUARD_2; ++i)
                                         {
                                             if (Creature* guard = instance->GetCreature(GetGuidData(i)))
-                                                guard->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                                guard->SetImmuneToAll(false);
                                         }
 
                                         if (Creature* erekem = GetCreature(DATA_EREKEM))
                                         {
-                                            erekem->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                            erekem->SetImmuneToAll(false);
                                             erekem->AI()->DoZoneInCombat(erekem, 200.0f);
                                         }
                                     });
@@ -618,7 +618,7 @@ class instance_violet_hold : public InstanceMapScript
                                 {
                                     if (Creature* ichoron = GetCreature(DATA_ICHORON))
                                     {
-                                        ichoron->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                        ichoron->SetImmuneToAll(false);
                                         ichoron->AI()->DoZoneInCombat(ichoron, 200.0f);
                                     }
                                 });
@@ -640,7 +640,7 @@ class instance_violet_hold : public InstanceMapScript
                                 {
                                     if (Creature* lavanthor = GetCreature(DATA_LAVANTHOR))
                                     {
-                                        lavanthor->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                        lavanthor->SetImmuneToAll(false);
                                         lavanthor->AI()->DoZoneInCombat(lavanthor, 200.0f);
                                     }
                                 });
@@ -667,7 +667,7 @@ class instance_violet_hold : public InstanceMapScript
                                     {
                                         if (Creature* xevozz = GetCreature(DATA_XEVOZZ))
                                         {
-                                            xevozz->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                            xevozz->SetImmuneToAll(false);
                                             xevozz->AI()->DoZoneInCombat(xevozz, 200.0f);
                                         }
                                     });
@@ -693,7 +693,7 @@ class instance_violet_hold : public InstanceMapScript
                                 {
                                     if (Creature* zuramat = GetCreature(DATA_ZURAMAT))
                                     {
-                                        zuramat->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                        zuramat->SetImmuneToAll(false);
                                         zuramat->AI()->DoZoneInCombat(zuramat, 200.0f);
                                     }
                                 });
@@ -733,7 +733,7 @@ class instance_violet_hold : public InstanceMapScript
                                     UpdateKilledBoss(guard);
 
                                 guard->GetMotionMaster()->MoveTargetedHome();
-                                guard->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                guard->SetImmuneToAll(true);
                             }
                         }
                         // no break
@@ -746,7 +746,7 @@ class instance_violet_hold : public InstanceMapScript
                         }
 
                         boss->GetMotionMaster()->MoveTargetedHome();
-                        boss->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                        boss->SetImmuneToAll(true);
                         break;
                 }
             }
@@ -901,7 +901,7 @@ class instance_violet_hold : public InstanceMapScript
                             {
                                 cyanigosa->RemoveAurasDueToSpell(SPELL_CYANIGOSA_ARCANE_POWER_STATE);
                                 cyanigosa->CastSpell(cyanigosa, SPELL_CYANIGOSA_TRANSFORM, true);
-                                cyanigosa->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                                cyanigosa->SetImmuneToAll(false);
                             }
                         });
                     });
diff --git a/src/server/scripts/Northrend/zone_borean_tundra.cpp b/src/server/scripts/Northrend/zone_borean_tundra.cpp
index 50818339887..fccc0a8f437 100644
--- a/src/server/scripts/Northrend/zone_borean_tundra.cpp
+++ b/src/server/scripts/Northrend/zone_borean_tundra.cpp
@@ -727,7 +727,7 @@ public:
             owner->CastSpell(owner, SPELL_SUBDUED, true);
             GetCaster()->CastSpell(GetCaster(), SPELL_DRAKE_HATCHLING_SUBDUED, true);
             owner->SetFaction(35);
-            owner->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+            owner->SetImmuneToAll(true);
             owner->DespawnOrUnsummon(3 * MINUTE*IN_MILLISECONDS);
         }
 
diff --git a/src/server/scripts/Northrend/zone_dragonblight.cpp b/src/server/scripts/Northrend/zone_dragonblight.cpp
index e8b70b98010..43983271833 100644
--- a/src/server/scripts/Northrend/zone_dragonblight.cpp
+++ b/src/server/scripts/Northrend/zone_dragonblight.cpp
@@ -550,7 +550,7 @@ class npc_wyrmrest_defender : public CreatureScript
                 {
                     case SPELL_WYRMREST_DEFENDER_MOUNT:
                         Talk(WHISPER_MOUNTED, me->GetCharmerOrOwner());
-                        me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC | UNIT_FLAG_IMMUNE_TO_NPC);
+                        me->SetImmuneToAll(false);
                         me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_PVP_ATTACKABLE);
                         break;
                     // Both below are for checking low hp warning
diff --git a/src/server/scripts/Northrend/zone_grizzly_hills.cpp b/src/server/scripts/Northrend/zone_grizzly_hills.cpp
index 78be007420d..f4749ef74f4 100644
--- a/src/server/scripts/Northrend/zone_grizzly_hills.cpp
+++ b/src/server/scripts/Northrend/zone_grizzly_hills.cpp
@@ -373,7 +373,7 @@ public:
                 if (me->FindNearestGameObject(OBJECT_HAUNCH, 2.0f))
                 {
                     me->SetStandState(UNIT_STAND_STATE_DEAD);
-                    me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                    me->SetImmuneToPC(true);
                     me->SetUInt32Value(UNIT_DYNAMIC_FLAGS, UNIT_DYNFLAG_DEAD);
                 }
                 _phase = 0;
@@ -568,7 +568,8 @@ public:
         {
             _playerGUID.Clear();
 
-            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+            me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+            me->SetImmuneToPC(false);
             me->SetReactState(REACT_AGGRESSIVE);
         }
 
@@ -618,7 +619,8 @@ public:
         {
             if (spell->Id == SPELL_SMOKE_BOMB && caster->GetTypeId() == TYPEID_PLAYER)
             {
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
+                me->SetImmuneToPC(true);
                 me->SetReactState(REACT_PASSIVE);
                 me->CombatStop(false);
                 _playerGUID = caster->GetGUID();
diff --git a/src/server/scripts/Northrend/zone_storm_peaks.cpp b/src/server/scripts/Northrend/zone_storm_peaks.cpp
index 5bc39c7e47d..efe1691d479 100644
--- a/src/server/scripts/Northrend/zone_storm_peaks.cpp
+++ b/src/server/scripts/Northrend/zone_storm_peaks.cpp
@@ -719,7 +719,7 @@ class npc_wild_wyrm : public CreatureScript
 
                 InitSpellsForPhase();
 
-                me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(false);
             }
 
             void DoAction(int32 action) override
@@ -758,7 +758,7 @@ class npc_wild_wyrm : public CreatureScript
 
                 _playerGuid = caster->GetGUID();
                 DoCastAOE(SPELL_FULL_HEAL_MANA, true);
-                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_IMMUNE_TO_PC);
+                me->SetImmuneToPC(true);
 
                 me->GetMotionMaster()->MovePoint(POINT_START_FIGHT, *caster);
             }