Core/Creatures: Various fixes for creatures, regarding combat conditions, despawning, and few others (#18998)

* Made some changes to kiting mechanics, simplified code and made taunt auras prolong combat no matter the distance from the spawn
Unified some creature despawning code, removed some brutal direct calls in scripts
Don't play death anim on forced despawn
Removed some redundant visibility changes on creature despawn
Fixed possible problem with pet initializing template info from difficulty greater than normal
Properly keep UNIT_FLAG_IN_COMBAT on UpdateEntry call
Moved RegenerateMana function to general Regenerate(Power) function
Fixed increased health regeneration from polymorph for pets
Implemented CREATURE_TYPE_FLAG_GHOST_VISIBLE, those creatures will be properly seen when player is dead also
Removed hackfix from Gaeriyan and Franclorn Forgewright, fixed properly
Simplified ForcedRespawnTime code in ForcedDespawn
Do not allow to assist unit while evading or when enemy is evading
Do not allow to attack other units when evading or when the unit is evading
Corrected distance checking code before creature is allowed to evade, should fix some common problems
Properly return summon position for summoned creatures as their respawn position
Properly stop all moving units on gossip hello, no matter their npc flags

(cherrypicked from e1f14215d86fc9f0cd041f0e87bf0a689c086329)

7 files changed, 15 insertions, 30 deletions

diff --git a/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_hydross_the_unstable.cpp b/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_hydross_the_unstable.cpp
index d40f46bbaaa..5617e708b10 100644
--- a/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_hydross_the_unstable.cpp
+++ b/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_hydross_the_unstable.cpp
@@ -172,8 +172,7 @@ public:
             {
                 if (Creature* mob = ObjectAccessor::GetCreature(*me, beams[i]))
                 {
-                    mob->setDeathState(DEAD);
-                    mob->RemoveCorpse();
+                    mob->DespawnOrUnsummon();
                 }
             }
         }
diff --git a/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_lady_vashj.cpp b/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_lady_vashj.cpp
index 211be3d55f2..4a5c82d0c75 100644
--- a/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_lady_vashj.cpp
+++ b/src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_lady_vashj.cpp
@@ -805,9 +805,9 @@ public:
                 if (!Vashj || !Vashj->IsAlive() || ENSURE_AI(boss_lady_vashj::boss_lady_vashjAI, Vashj->ToCreature()->AI())->Phase != 3)
                 {
                     // remove
-                    me->setDeathState(DEAD);
-                    me->RemoveCorpse();
                     me->setFaction(35);
+                    me->DespawnOrUnsummon();
+                    return;
                 }
 
                 CheckTimer = 1000;
diff --git a/src/server/scripts/Outland/HellfireCitadel/ShatteredHalls/boss_warchief_kargath_bladefist.cpp b/src/server/scripts/Outland/HellfireCitadel/ShatteredHalls/boss_warchief_kargath_bladefist.cpp
index c5df85fc291..51082af5744 100644
--- a/src/server/scripts/Outland/HellfireCitadel/ShatteredHalls/boss_warchief_kargath_bladefist.cpp
+++ b/src/server/scripts/Outland/HellfireCitadel/ShatteredHalls/boss_warchief_kargath_bladefist.cpp
@@ -179,11 +179,7 @@ class boss_warchief_kargath_bladefist : public CreatureScript
                 {
                     Creature* creature = ObjectAccessor::GetCreature(*me, *itr);
                     if (creature && creature->IsAlive())
-                    {
-                        creature->GetMotionMaster()->Clear(true);
-                        me->DealDamage(creature, creature->GetHealth(), NULL, DIRECT_DAMAGE, SPELL_SCHOOL_MASK_NORMAL, NULL, false);
-                        creature->RemoveCorpse();
-                    }
+                        creature->DespawnOrUnsummon();
                 }
                 adds.clear();
 
@@ -191,11 +187,7 @@ class boss_warchief_kargath_bladefist : public CreatureScript
                 {
                     Creature* creature = ObjectAccessor::GetCreature(*me, *itr);
                     if (creature && creature->IsAlive())
-                    {
-                        creature->GetMotionMaster()->Clear(true);
-                        me->DealDamage(creature, creature->GetHealth(), NULL, DIRECT_DAMAGE, SPELL_SCHOOL_MASK_NORMAL, NULL, false);
-                        creature->RemoveCorpse();
-                    }
+                        creature->DespawnOrUnsummon();
                 }
                 assassins.clear();
             }
diff --git a/src/server/scripts/Outland/TempestKeep/Mechanar/boss_nethermancer_sepethrea.cpp b/src/server/scripts/Outland/TempestKeep/Mechanar/boss_nethermancer_sepethrea.cpp
index 175caeb0dea..f66c90eead0 100644
--- a/src/server/scripts/Outland/TempestKeep/Mechanar/boss_nethermancer_sepethrea.cpp
+++ b/src/server/scripts/Outland/TempestKeep/Mechanar/boss_nethermancer_sepethrea.cpp
@@ -196,8 +196,8 @@ class npc_ragin_flames : public CreatureScript
                         if (instance->GetData(DATA_NETHERMANCER_SEPRETHREA) != IN_PROGRESS)
                         {
                             //remove
-                            me->setDeathState(JUST_DIED);
-                            me->RemoveCorpse();
+                            me->DespawnOrUnsummon();
+                            return;
                         }
                         Check_Timer = 1000;
                     } else Check_Timer -= diff;
diff --git a/src/server/scripts/Outland/TempestKeep/Mechanar/boss_pathaleon_the_calculator.cpp b/src/server/scripts/Outland/TempestKeep/Mechanar/boss_pathaleon_the_calculator.cpp
index 251954cbb73..449dc48fac4 100644
--- a/src/server/scripts/Outland/TempestKeep/Mechanar/boss_pathaleon_the_calculator.cpp
+++ b/src/server/scripts/Outland/TempestKeep/Mechanar/boss_pathaleon_the_calculator.cpp
@@ -232,8 +232,8 @@ class npc_nether_wraith : public CreatureScript
                 {
                     if (Die_Timer <= diff)
                     {
-                        me->setDeathState(JUST_DIED);
-                        me->RemoveCorpse();
+                        me->DespawnOrUnsummon();
+                        return;
                     }
                     else
                         Die_Timer -= diff;
diff --git a/src/server/scripts/Outland/zone_blades_edge_mountains.cpp b/src/server/scripts/Outland/zone_blades_edge_mountains.cpp
index 0c00d733bcb..4f9f1f18da9 100644
--- a/src/server/scripts/Outland/zone_blades_edge_mountains.cpp
+++ b/src/server/scripts/Outland/zone_blades_edge_mountains.cpp
@@ -123,11 +123,7 @@ public:
                 return;
 
             if (id == 0)
-            {
-                me->setDeathState(JUST_DIED);
-                me->RemoveCorpse();
-                me->SetHealth(0);
-            }
+                me->DespawnOrUnsummon(1);
         }
 
         void SpellHit(Unit* caster, const SpellInfo* spell) override
@@ -155,7 +151,8 @@ public:
                         EnterEvadeMode();
                         me->AddUnitFlag(UNIT_FLAG_NON_ATTACKABLE);
                         IsNihil = true;
-                    }else
+                    }
+                    else
                         AttackStart(caster);
                 }
             }
diff --git a/src/server/scripts/Outland/zone_shadowmoon_valley.cpp b/src/server/scripts/Outland/zone_shadowmoon_valley.cpp
index 025b0ece9e4..5107eb8dac1 100644
--- a/src/server/scripts/Outland/zone_shadowmoon_valley.cpp
+++ b/src/server/scripts/Outland/zone_shadowmoon_valley.cpp
@@ -384,7 +384,6 @@ public:
 
             FlyTimer = 10000;
             me->SetDisableGravity(false);
-            me->SetVisible(true);
         }
 
         void SpellHit(Unit* caster, const SpellInfo* spell) override
@@ -428,10 +427,8 @@ public:
 
                     PlayerGUID.Clear();
                 }
-                me->SetVisible(false);
-                me->SetDisableGravity(false);
-                me->DealDamage(me, me->GetHealth(), NULL, DIRECT_DAMAGE, SPELL_SCHOOL_MASK_NORMAL, NULL, false);
-                me->RemoveCorpse();
+
+                me->DespawnOrUnsummon(1);
             }
         }
 
@@ -1197,7 +1194,7 @@ public:
 
         void JustDied(Unit* /*killer*/) override
         {
-            me->RemoveCorpse();
+            me->DespawnOrUnsummon();
             if (Creature* LordIllidan = (ObjectAccessor::GetCreature(*me, LordIllidanGUID)))
                 ENSURE_AI(npc_lord_illidan_stormrage::npc_lord_illidan_stormrageAI, LordIllidan->AI())->LiveCounter();
         }