Core/Misc: A variety of clean-up changes, mostly following up on 532ab1c to fix legacy bugs exposed by it:

- Triggers can no longer have a threat list (this may expose some ugliness in old legacy scripts)
- Threat entries are forced to OFFLINE if the AI refuses to attack the target
- Clean up passive creature evade behavior to be more consistent
- Fix a months old issue in spawn group management that would cause "Inactive" to incorrectly show in .list respawns for system groups outside of map 0
- Valithria script cleanups, remove old hacks and make it work with the new system. Closes #21174.
- Some strings cleanup

(cherry picked from commit 9f9507e6a1fd50a5ce643a4096c1712700244a61)

6 files changed, 54 insertions, 61 deletions

diff --git a/src/server/game/AI/CreatureAI.cpp b/src/server/game/AI/CreatureAI.cpp
index 2c07dcd551d..6e337ff8c5d 100644
--- a/src/server/game/AI/CreatureAI.cpp
+++ b/src/server/game/AI/CreatureAI.cpp
@@ -84,11 +84,12 @@ void CreatureAI::DoZoneInCombat(Creature* creature /*= nullptr*/, float maxRange
             {
                 if (Unit* summoner = creature->ToTempSummon()->GetSummoner())
                 {
-                    Unit* target = summoner->getAttackerForHelper();
-                    if (!target && !summoner->GetThreatManager().IsThreatListEmpty())
-                        target = summoner->GetThreatManager().GetAnyTarget();
-                    if (target && (creature->IsFriendlyTo(summoner) || creature->IsHostileTo(target)))
-                        creature->AI()->AttackStart(target);
+                    if (creature->IsFriendlyTo(summoner))
+                    {
+                        Unit* target = summoner->getAttackerForHelper();
+                        if (target && creature->IsHostileTo(target))
+                            creature->AI()->AttackStart(target);
+                    }
                 }
             }
         }
@@ -109,7 +110,7 @@ void CreatureAI::DoZoneInCombat(Creature* creature /*= nullptr*/, float maxRange
     for (Map::PlayerList::const_iterator itr = playerList.begin(); itr != playerList.end(); ++itr)
         if (Player* player = itr->GetSource())
             if (player->IsAlive())
-                creature->SetInCombatWith(player);
+                creature->EngageWithTarget(player);
 }
 
 // scripts does not take care about MoveInLineOfSight loops
@@ -237,12 +238,12 @@ bool CreatureAI::UpdateVictim()
 
         return me->GetVictim() != nullptr;
     }
-    else if (me->GetThreatManager().IsThreatListEmpty(true))
+    else if (!me->IsInCombat())
     {
         EnterEvadeMode(EVADE_REASON_NO_HOSTILES);
         return false;
     }
-    else
+    else if (me->GetVictim())
         me->AttackStop();
 
     return true;
diff --git a/src/server/game/Combat/ThreatManager.cpp b/src/server/game/Combat/ThreatManager.cpp
index 16511b14a3b..03d12c12def 100644
--- a/src/server/game/Combat/ThreatManager.cpp
+++ b/src/server/game/Combat/ThreatManager.cpp
@@ -94,6 +94,8 @@ ThreatReference::OnlineState ThreatReference::SelectOnlineState()
         return ONLINE_STATE_OFFLINE;
     if (!FlagsAllowFighting(_owner, _victim) || !FlagsAllowFighting(_victim, _owner))
         return ONLINE_STATE_OFFLINE;
+    if (_owner->IsAIEnabled && !_owner->GetAI()->CanAIAttack(_victim))
+        return ONLINE_STATE_OFFLINE;
     // next, check suppression (immunity to chosen melee attack school)
     if (_victim->IsImmunedToDamage(_owner->GetMeleeDamageSchoolMask()))
         return ONLINE_STATE_SUPPRESSED;
@@ -135,16 +137,17 @@ void ThreatReference::ClearThreat(bool sendRemove)
 
 /*static*/ bool ThreatManager::CanHaveThreatList(Unit const* who)
 {
+    Creature const* cWho = who->ToCreature();
     // only creatures can have threat list
-    if (who->GetTypeId() != TYPEID_UNIT)
+    if (!cWho)
         return false;
 
-    // pets and totems cannot have threat list
-    if (who->IsPet() || who->IsTotem())
+    // pets, totems and triggers cannot have threat list
+    if (cWho->IsPet() || cWho->IsTotem() || cWho->IsTrigger())
         return false;
 
     // summons cannot have a threat list, unless they are controlled by a creature
-    if (who->HasUnitTypeMask(UNIT_MASK_MINION | UNIT_MASK_GUARDIAN) && !who->GetOwnerGUID().IsCreature())
+    if (cWho->HasUnitTypeMask(UNIT_MASK_MINION | UNIT_MASK_GUARDIAN) && !cWho->GetOwnerGUID().IsCreature())
         return false;
 
     return true;
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index e6fd20e73aa..585dbe4a6ce 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -678,7 +678,7 @@ bool Creature::UpdateEntry(uint32 entry, CreatureData const* data /*= nullptr*/,
 
 void Creature::Update(uint32 diff)
 {
-    if (IsAIEnabled && m_triggerJustAppeared && m_deathState == ALIVE)
+    if (IsAIEnabled && m_triggerJustAppeared && m_deathState != DEAD)
     {
         if (m_respawnCompatibilityMode && m_vehicleKit)
             m_vehicleKit->Reset();
diff --git a/src/server/game/Maps/Map.cpp b/src/server/game/Maps/Map.cpp
index 8d6d2e8f663..557bec6dbd0 100644
--- a/src/server/game/Maps/Map.cpp
+++ b/src/server/game/Maps/Map.cpp
@@ -3396,7 +3396,7 @@ void Map::ApplyDynamicModeRespawnScaling(WorldObject const* obj, ObjectGuid::Low
 SpawnGroupTemplateData const* Map::GetSpawnGroupData(uint32 groupId) const
 {
     SpawnGroupTemplateData const* data = sObjectMgr->GetSpawnGroupData(groupId);
-    if (data && data->mapId == GetId())
+    if (data && (data->flags & SPAWNGROUP_FLAG_SYSTEM || data->mapId == GetId()))
         return data;
     return nullptr;
 }
@@ -3527,11 +3527,12 @@ bool Map::IsSpawnGroupActive(uint32 groupId) const
     SpawnGroupTemplateData const* const data = GetSpawnGroupData(groupId);
     if (!data)
     {
-        TC_LOG_WARN("maps", "Tried to query state of non-existing spawn group %u on map %u.", groupId, GetId());
+        TC_LOG_ERROR("maps", "Tried to query state of non-existing spawn group %u on map %u.", groupId, GetId());
         return false;
     }
     if (data->flags & SPAWNGROUP_FLAG_SYSTEM)
         return true;
+    // either manual spawn group and toggled, or not manual spawn group and not toggled...
     return (_toggledSpawnGroupIds.find(groupId) != _toggledSpawnGroupIds.end()) != !(data->flags & SPAWNGROUP_FLAG_MANUAL_SPAWN);
 }
 
diff --git a/src/server/scripts/Commands/cs_debug.cpp b/src/server/scripts/Commands/cs_debug.cpp
index b46b8cfd978..8efbd353ed0 100644
--- a/src/server/scripts/Commands/cs_debug.cpp
+++ b/src/server/scripts/Commands/cs_debug.cpp
@@ -856,8 +856,6 @@ public:
             handler->PSendSysMessage("%s (%s) is not alive.", target->GetName().c_str(), target->GetGUID().ToString().c_str());
             return true;
         }
-        if (!target->CanHaveThreatList())
-            handler->PSendSysMessage("%s (%s) cannot have a threat list.", target->GetName().c_str(), target->GetGUID().ToString().c_str());
 
         uint32 count = 0;
         auto const& threatenedByMe = target->GetThreatManager().GetThreatenedByMeList();
@@ -875,8 +873,8 @@ public:
         }
 
         if (!mgr.CanHaveThreatList())
-            return true;
-        if (mgr.IsEngaged())
+            handler->PSendSysMessage("%s (%s) cannot have a threat list.", target->GetName().c_str(), target->GetGUID().ToString().c_str());
+        else if (mgr.IsEngaged())
         {
             count = 0;
             handler->PSendSysMessage("Threat list of %s (%s, SpawnID %u)", target->GetName().c_str(), target->GetGUID().ToString().c_str(), target->GetTypeId() == TYPEID_UNIT ? target->ToCreature()->GetSpawnId() : 0);
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp
index 01213a9009d..1ebd8a54307 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp
@@ -230,44 +230,10 @@ class ValithriaDespawner : public BasicEvent
 
         void operator()(Creature* creature) const
         {
-            switch (creature->GetEntry())
-            {
-                case NPC_VALITHRIA_DREAMWALKER:
-                    if (InstanceScript* instance = creature->GetInstanceScript())
-                        instance->SendEncounterUnit(ENCOUNTER_FRAME_DISENGAGE, creature);
-                    break;
-                case NPC_BLAZING_SKELETON:
-                case NPC_SUPPRESSER:
-                case NPC_BLISTERING_ZOMBIE:
-                case NPC_GLUTTONOUS_ABOMINATION:
-                case NPC_MANA_VOID:
-                case NPC_COLUMN_OF_FROST:
-                case NPC_ROT_WORM:
-                    creature->DespawnOrUnsummon();
-                    return;
-                case NPC_RISEN_ARCHMAGE:
-                    if (!creature->GetSpawnId())
-                    {
-                        creature->DespawnOrUnsummon();
-                        return;
-                    }
-                    creature->Respawn(true);
-                    break;
-                default:
-                    return;
-            }
-
-            uint32 corpseDelay = creature->GetCorpseDelay();
-            uint32 respawnDelay = creature->GetRespawnDelay();
-            creature->SetCorpseDelay(1);
-            creature->SetRespawnDelay(10);
-
-            if (CreatureData const* data = creature->GetCreatureData())
-                creature->UpdatePosition(data->spawnPoint);
-            creature->DespawnOrUnsummon();
-
-            creature->SetCorpseDelay(corpseDelay);
-            creature->SetRespawnDelay(respawnDelay);
+            if (creature->GetEntry() == NPC_VALITHRIA_DREAMWALKER)
+                if (InstanceScript* instance = creature->GetInstanceScript())
+                    instance->SendEncounterUnit(ENCOUNTER_FRAME_DISENGAGE, creature);
+            creature->DespawnOrUnsummon(0, 10s);
         }
 
     private:
@@ -365,7 +331,7 @@ class boss_valithria_dreamwalker : public CreatureScript
                 }
                 else if (_instance->GetBossState(DATA_VALITHRIA_DREAMWALKER) == NOT_STARTED)
                     if (Creature* archmage = me->FindNearestCreature(NPC_RISEN_ARCHMAGE, 30.0f))
-                        archmage->AI()->DoZoneInCombat();   // call JustEngagedWith on one of them, that will make it all start
+                        archmage->EngageWithTarget(healer);   // call JustEngagedWith on one of them, that will make it all start
             }
 
             void DamageTaken(Unit* /*attacker*/, uint32& damage) override
@@ -628,8 +594,9 @@ class npc_the_lich_king_controller : public CreatureScript
             {
                 // must not be in dream phase
                 PhasingHandler::RemovePhase(summon, 173, true);
+                summon->AI()->DoZoneInCombat();
                 if (summon->GetEntry() != NPC_SUPPRESSER)
-                    if (Unit* target = SelectTarget(SELECT_TARGET_RANDOM, 0, 0.0f, true))
+                    if (Unit* target = me->GetCombatManager().GetAnyTarget())
                         summon->AI()->AttackStart(target);
             }
 
@@ -711,7 +678,7 @@ class npc_risen_archmage : public CreatureScript
                 Initialize();
             }
 
-            void JustEngagedWith(Unit* /*target*/) override
+            void JustEngagedWith(Unit* target) override
             {
                 me->FinishSpell(CURRENT_CHANNELED_SPELL, false);
                 if (me->GetSpawnId() && _canCallJustEngagedWith)
@@ -724,10 +691,16 @@ class npc_risen_archmage : public CreatureScript
                         (*itr)->AI()->DoAction(ACTION_ENTER_COMBAT);
 
                     if (Creature* lichKing = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_VALITHRIA_LICH_KING)))
+                    {
+                        lichKing->EngageWithTarget(target);
                         lichKing->AI()->DoZoneInCombat();
+                    }
 
                     if (Creature* trigger = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_VALITHRIA_TRIGGER)))
+                    {
+                        trigger->EngageWithTarget(target);
                         trigger->AI()->DoZoneInCombat();
+                    }
                 }
             }
 
@@ -883,7 +856,24 @@ class npc_suppresser : public CreatureScript
             void IsSummonedBy(Unit* /*summoner*/) override
             {
                 if (Creature* valithria = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_VALITHRIA_DREAMWALKER)))
-                    AttackStart(valithria);
+                {
+                    float x, y, z;
+                    valithria->GetContactPoint(me, x,y,z);
+                    me->GetMotionMaster()->MovePoint(42, x, y, z);
+                }
+            }
+
+            void MovementInform(uint32 /*type*/, uint32 id)
+            {
+                if (id == 42)
+                {
+                    me->SetReactState(REACT_AGGRESSIVE);
+                    if (Creature* valithria = ObjectAccessor::GetCreature(*me, _instance->GetGuidData(DATA_VALITHRIA_DREAMWALKER)))
+                    {
+                        AttackStart(valithria);
+                        DoCastAOE(SPELL_SUPPRESSION);
+                    }
+                }
             }
 
             void UpdateAI(uint32 diff) override