Core/AI: Finally move the "is creature engaged" flag to be a property of the creature AI, where it honestly always belonged. Fixes #17981 and #23602 for real this time.

(cherry picked from commit 0e7c66cb4c7ff7d44e232d0b50703a48605ffd24)

16 files changed, 122 insertions, 63 deletions

diff --git a/src/server/game/AI/CoreAI/GuardAI.cpp b/src/server/game/AI/CoreAI/GuardAI.cpp
index 214c8df86f7..aa6ea0e93c4 100644
--- a/src/server/game/AI/CoreAI/GuardAI.cpp
+++ b/src/server/game/AI/CoreAI/GuardAI.cpp
@@ -52,7 +52,7 @@ void GuardAI::EnterEvadeMode(EvadeReason /*why*/)
     {
         me->GetMotionMaster()->MoveIdle();
         me->CombatStop(true);
-        me->GetThreatManager().NotifyDisengaged();
+        EngagementOver();
         return;
     }
 
@@ -60,7 +60,7 @@ void GuardAI::EnterEvadeMode(EvadeReason /*why*/)
 
     me->RemoveAllAuras();
     me->CombatStop(true);
-    me->GetThreatManager().NotifyDisengaged();
+    EngagementOver();
 
     me->GetMotionMaster()->MoveTargetedHome();
 }
diff --git a/src/server/game/AI/CoreAI/PassiveAI.h b/src/server/game/AI/CoreAI/PassiveAI.h
index 582fb737d41..039a5293036 100644
--- a/src/server/game/AI/CoreAI/PassiveAI.h
+++ b/src/server/game/AI/CoreAI/PassiveAI.h
@@ -39,6 +39,9 @@ class TC_GAME_API PossessedAI : public CreatureAI
 
         void MoveInLineOfSight(Unit*) override { }
         void AttackStart(Unit* target) override;
+        void JustEnteredCombat(Unit* who) override { EngagementStart(who); }
+        void JustExitedCombat() override { EngagementOver(); }
+        void JustStartedThreateningMe(Unit*) override { }
         void UpdateAI(uint32) override;
         void EnterEvadeMode(EvadeReason /*why*/) override { }
 
@@ -55,6 +58,8 @@ class TC_GAME_API NullCreatureAI : public CreatureAI
 
         void MoveInLineOfSight(Unit*) override { }
         void AttackStart(Unit*) override { }
+        void JustStartedThreateningMe(Unit*) override { }
+        void JustEnteredCombat(Unit*) override { }
         void UpdateAI(uint32) override { }
         void JustAppeared() override { }
         void EnterEvadeMode(EvadeReason /*why*/) override { }
diff --git a/src/server/game/AI/CoreAI/TotemAI.cpp b/src/server/game/AI/CoreAI/TotemAI.cpp
index 48940a1412b..64741e5993a 100644
--- a/src/server/game/AI/CoreAI/TotemAI.cpp
+++ b/src/server/game/AI/CoreAI/TotemAI.cpp
@@ -33,16 +33,9 @@ int32 TotemAI::Permissible(Creature const* creature)
     return PERMIT_BASE_NO;
 }
 
-TotemAI::TotemAI(Creature* creature, uint32 scriptId) : CreatureAI(creature, scriptId), _victimGUID()
+TotemAI::TotemAI(Creature* creature, uint32 scriptId) : NullCreatureAI(creature, scriptId), _victimGUID()
 {
-    ASSERT(creature->IsTotem(), "TotemAI: AI assigned to a no-totem creature (%s)!", creature->GetGUID().ToString().c_str());
-}
-
-void TotemAI::MoveInLineOfSight(Unit* /*who*/) { }
-
-void TotemAI::EnterEvadeMode(EvadeReason /*why*/)
-{
-    me->CombatStop(true);
+    ASSERT(creature->IsTotem(), "TotemAI: AI assigned to a non-totem creature (%s)!", creature->GetGUID().ToString().c_str());
 }
 
 void TotemAI::UpdateAI(uint32 /*diff*/)
diff --git a/src/server/game/AI/CoreAI/TotemAI.h b/src/server/game/AI/CoreAI/TotemAI.h
index dcc14e963ee..80f387f6a22 100644
--- a/src/server/game/AI/CoreAI/TotemAI.h
+++ b/src/server/game/AI/CoreAI/TotemAI.h
@@ -19,20 +19,18 @@
 #define TRINITY_TOTEMAI_H
 
 #include "CreatureAI.h"
+#include "PassiveAI.h"
 #include "Timer.h"
 
 class Creature;
 class Totem;
 
-class TC_GAME_API TotemAI : public CreatureAI
+class TC_GAME_API TotemAI : public NullCreatureAI
 {
     public:
         explicit TotemAI(Creature* creature, uint32 scriptId = {});
 
-        void MoveInLineOfSight(Unit* who) override;
         void AttackStart(Unit* victim) override;
-        void JustAppeared() override { }
-        void EnterEvadeMode(EvadeReason /*why*/) override;
 
         void UpdateAI(uint32 diff) override;
         static int32 Permissible(Creature const* creature);
diff --git a/src/server/game/AI/CoreAI/UnitAI.cpp b/src/server/game/AI/CoreAI/UnitAI.cpp
index df37aa94f03..642ac34a675 100644
--- a/src/server/game/AI/CoreAI/UnitAI.cpp
+++ b/src/server/game/AI/CoreAI/UnitAI.cpp
@@ -318,7 +318,7 @@ std::string UnitAI::GetDebugInfo() const
 }
 
 DefaultTargetSelector::DefaultTargetSelector(Unit const* unit, float dist, bool playerOnly, bool withTank, int32 aura)
-    : _me(unit), _dist(dist), _playerOnly(playerOnly), _exception(!withTank ? _me->GetThreatManager().GetCurrentVictim() : nullptr), _aura(aura)
+    : _me(unit), _dist(dist), _playerOnly(playerOnly), _exception(!withTank ? unit->GetThreatManager().GetLastVictim() : nullptr), _aura(aura)
 {
 }
 
diff --git a/src/server/game/AI/CreatureAI.cpp b/src/server/game/AI/CreatureAI.cpp
index e1d53238c89..7d617a9c384 100644
--- a/src/server/game/AI/CreatureAI.cpp
+++ b/src/server/game/AI/CreatureAI.cpp
@@ -43,7 +43,7 @@ AISpellInfoType* GetAISpellInfo(uint32 spellId, Difficulty difficulty)
 
 CreatureAI::CreatureAI(Creature* creature, uint32 scriptId)
     : UnitAI(creature), me(creature), _boundary(nullptr),
-      _negateBoundary(false), _scriptId(scriptId ? scriptId : creature->GetScriptId()), _moveInLOSLocked(false)
+      _negateBoundary(false), _scriptId(scriptId ? scriptId : creature->GetScriptId()), _isEngaged(false), _moveInLOSLocked(false)
 {
     ASSERT(_scriptId, "A CreatureAI was initialized with an invalid scriptId!");
 }
@@ -207,6 +207,12 @@ void CreatureAI::JustAppeared()
     }
 }
 
+void CreatureAI::JustEnteredCombat(Unit* who)
+{
+    if (!IsEngaged() && !me->CanHaveThreatList())
+        EngagementStart(who);
+}
+
 void CreatureAI::EnterEvadeMode(EvadeReason why)
 {
     if (!_EnterEvadeMode(why))
@@ -235,7 +241,7 @@ void CreatureAI::EnterEvadeMode(EvadeReason why)
 
 bool CreatureAI::UpdateVictim()
 {
-    if (!me->IsEngaged())
+    if (!IsEngaged())
         return false;
 
     if (!me->HasReactState(REACT_PASSIVE))
@@ -257,22 +263,52 @@ bool CreatureAI::UpdateVictim()
     return true;
 }
 
+void CreatureAI::EngagementStart(Unit* who)
+{
+    if (_isEngaged)
+    {
+        TC_LOG_ERROR("scripts.ai", "CreatureAI::EngagementStart called even though creature is already engaged. Creature debug info:\n%s", me->GetDebugInfo().c_str());
+        return;
+    }
+    _isEngaged = true;
+
+    me->AtEngage(who);
+}
+
+void CreatureAI::EngagementOver()
+{
+    if (!_isEngaged)
+    {
+        TC_LOG_ERROR("scripts.ai", "CreatureAI::EngagementOver called even though creature is not currently engaged. Creature debug info:\n%s", me->GetDebugInfo().c_str());
+        return;
+    }
+    _isEngaged = false;
+
+    me->AtDisengage();
+}
+
 bool CreatureAI::_EnterEvadeMode(EvadeReason /*why*/)
 {
+    if (me->IsInEvadeMode())
+        return false;
+
     if (!me->IsAlive())
+    {
+        EngagementOver();
         return false;
+    }
 
     me->RemoveAurasOnEvade();
 
     me->CombatStop(true);
-    me->GetThreatManager().NotifyDisengaged();
     me->SetLootRecipient(nullptr);
     me->ResetPlayerDamageReq();
     me->SetLastDamagedTime(0);
     me->SetCannotReachTarget(false);
     me->DoNotReacquireTarget();
+    EngagementOver();
 
-    return !me->IsInEvadeMode();
+    return true;
 }
 
 Optional<QuestGiverStatus> CreatureAI::GetDialogStatus(Player* /*player*/)
diff --git a/src/server/game/AI/CreatureAI.h b/src/server/game/AI/CreatureAI.h
index 165b905803e..eef2cc0bd6b 100644
--- a/src/server/game/AI/CreatureAI.h
+++ b/src/server/game/AI/CreatureAI.h
@@ -84,6 +84,8 @@ class TC_GAME_API CreatureAI : public UnitAI
         // Gets the id of the AI (script id)
         uint32 GetId() const { return _scriptId; }
 
+        bool IsEngaged() const { return _isEngaged; }
+
         void Talk(uint8 id, WorldObject const* whisperTarget = nullptr);
 
         /// == Reactions At =================================
@@ -97,11 +99,17 @@ class TC_GAME_API CreatureAI : public UnitAI
         // Called for reaction at stopping attack at no attackers or targets
         virtual void EnterEvadeMode(EvadeReason why = EVADE_REASON_OTHER);
 
+        // Called for reaction whenever we start being in combat (overridden from base UnitAI)
+        void JustEnteredCombat(Unit* /*who*/) override;
+
+        // Called for reaction whenever a new non-offline unit is added to the threat list
+        virtual void JustStartedThreateningMe(Unit* who) { if (!IsEngaged()) EngagementStart(who); }
+
         // Called for reaction when initially engaged - this will always happen _after_ JustEnteredCombat
         virtual void JustEngagedWith(Unit* /*who*/) { }
 
         // Called when the creature is killed
-        virtual void JustDied(Unit* /*killer*/) { }
+        virtual void JustDied(Unit* /*killer*/) { if (IsEngaged()) EngagementOver(); }
 
         // Called when the creature kills a unit
         virtual void KilledUnit(Unit* /*victim*/) { }
@@ -227,6 +235,8 @@ class TC_GAME_API CreatureAI : public UnitAI
 
         // intended for encounter design/debugging. do not use for other purposes. expensive.
         int32 VisualizeBoundary(uint32 duration, Unit* owner = nullptr, bool fill = false) const;
+
+        // boundary system methods
         virtual bool CheckInRoom();
         CreatureBoundary const* GetBoundary() const { return _boundary; }
         void SetBoundary(CreatureBoundary const* boundary, bool negativeBoundaries = false);
@@ -235,6 +245,8 @@ class TC_GAME_API CreatureAI : public UnitAI
         bool IsInBoundary(Position const* who = nullptr) const;
 
     protected:
+        void EngagementStart(Unit* who);
+        void EngagementOver();
         virtual void MoveInLineOfSight(Unit* /*who*/);
 
         bool _EnterEvadeMode(EvadeReason why = EVADE_REASON_OTHER);
@@ -246,6 +258,7 @@ class TC_GAME_API CreatureAI : public UnitAI
         void OnOwnerCombatInteraction(Unit* target);
 
         uint32 const _scriptId;
+        bool _isEngaged;
         bool _moveInLOSLocked;
 };
 
diff --git a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
index 91efe5d5312..63592dd30ba 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
@@ -94,8 +94,9 @@ void EscortAI::EnterEvadeMode(EvadeReason /*why*/)
 {
     me->RemoveAllAuras();
     me->CombatStop(true);
-    me->GetThreatManager().NotifyDisengaged();
     me->SetLootRecipient(nullptr);
+    
+    EngagementOver();
 
     if (HasEscortState(STATE_ESCORT_ESCORTING))
     {
diff --git a/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp b/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
index 669022d8420..d8f0d972cd1 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
@@ -103,14 +103,18 @@ void FollowerAI::JustAppeared()
 void FollowerAI::EnterEvadeMode(EvadeReason /*why*/)
 {
     if (!me->IsAlive())
+    {
+        EngagementOver();
         return;
+    }
 
     me->RemoveAllAuras();
     me->CombatStop(true);
-    me->GetThreatManager().NotifyDisengaged();
     me->SetLootRecipient(nullptr);
     me->SetCannotReachTarget(false);
     me->DoNotReacquireTarget();
+    
+    EngagementOver();
 
     if (HasFollowState(STATE_FOLLOW_INPROGRESS))
     {
diff --git a/src/server/game/Combat/CombatManager.cpp b/src/server/game/Combat/CombatManager.cpp
index d6f7a55665b..a43bb72eca4 100644
--- a/src/server/game/Combat/CombatManager.cpp
+++ b/src/server/game/Combat/CombatManager.cpp
@@ -293,13 +293,8 @@ void CombatManager::EndAllPvPCombat()
 
 /*static*/ void CombatManager::NotifyAICombat(Unit* me, Unit* other)
 {
-    if (!me->IsAIEnabled())
-        return;
-    me->GetAI()->JustEnteredCombat(other);
-
-    if (Creature* cMe = me->ToCreature())
-        if (!cMe->CanHaveThreatList())
-            cMe->AI()->JustEngagedWith(other);
+    if (UnitAI* ai = me->GetAI())
+        ai->JustEnteredCombat(other);
 }
 
 void CombatManager::PutReference(ObjectGuid const& guid, CombatReference* ref)
@@ -336,14 +331,14 @@ bool CombatManager::UpdateOwnerCombatState() const
     {
         _owner->AddUnitFlag(UNIT_FLAG_IN_COMBAT);
         _owner->AtEnterCombat();
-        if (!_owner->CanHaveThreatList() && !_owner->IsEngaged())
+        if (_owner->GetTypeId() == TYPEID_UNIT)
             _owner->AtEngage(GetAnyTarget());
     }
     else
     {
         _owner->RemoveUnitFlag(UNIT_FLAG_IN_COMBAT);
         _owner->AtExitCombat();
-        if (_owner->IsEngaged() && !(_owner->ToCreature() && _owner->CanHaveThreatList() && _owner->ToCreature()->IsAIEnabled()))
+        if (_owner->GetTypeId() != TYPEID_UNIT)
             _owner->AtDisengage();
     }
 
diff --git a/src/server/game/Combat/ThreatManager.cpp b/src/server/game/Combat/ThreatManager.cpp
index 183142f1cd7..6ad8de0aabb 100644
--- a/src/server/game/Combat/ThreatManager.cpp
+++ b/src/server/game/Combat/ThreatManager.cpp
@@ -71,6 +71,7 @@ void ThreatReference::UpdateOffline()
     {
         _online = ShouldBeSuppressed() ? ONLINE_STATE_SUPPRESSED : ONLINE_STATE_ONLINE;
         HeapNotifyIncreased();
+        _mgr.RegisterForAIUpdate(this);
     }
 }
 
@@ -199,10 +200,11 @@ Unit* ThreatManager::GetCurrentVictim()
 {
     if (!_currentVictimRef || _currentVictimRef->ShouldBeOffline())
         UpdateVictim();
-    return const_cast<ThreatManager const*>(this)->GetCurrentVictim();
+    ASSERT(!_currentVictimRef || _currentVictimRef->IsAvailable());
+    return _currentVictimRef ? _currentVictimRef->GetVictim() : nullptr;
 }
 
-Unit* ThreatManager::GetCurrentVictim() const
+Unit* ThreatManager::GetLastVictim() const
 {
     if (_currentVictimRef && !_currentVictimRef->ShouldBeOffline())
         return _currentVictimRef->GetVictim();
@@ -244,7 +246,7 @@ float ThreatManager::GetThreat(Unit const* who, bool includeOffline) const
     return (includeOffline || it->second->IsAvailable()) ? it->second->GetThreat() : 0.0f;
 }
 
-std::vector<ThreatReference*> ThreatManager::GetModifiableThreatList() const
+std::vector<ThreatReference*> ThreatManager::GetModifiableThreatList()
 {
     std::vector<ThreatReference*> list;
     list.reserve(_myThreatListEntries.size());
@@ -394,16 +396,14 @@ void ThreatManager::AddThreat(Unit* target, float amount, SpellInfo const* spell
     PutThreatListRef(target->GetGUID(), ref);
     target->GetThreatManager().PutThreatenedByMeRef(_owner->GetGUID(), ref);
 
-    // afterwards, we evaluate whether this is an online reference (it might not be an acceptable target, but we need to add it to our threat list before we check!)
     ref->UpdateOffline();
-    if (ref->IsOnline()) // ...and if the ref is online it also gets the threat it should have
+    if (ref->IsOnline()) // we only add the threat if the ref is currently available
         ref->AddThreat(amount);
 
-    if (!_owner->IsEngaged())
-    {
-        _owner->AtEngage(target);
+    if (!_currentVictimRef)
         UpdateVictim();
-    }
+    else
+        ProcessAIUpdates();
 }
 
 void ThreatManager::ScaleThreat(Unit* target, float factor)
@@ -488,14 +488,6 @@ void ThreatManager::ClearAllThreat()
     }
 }
 
-void ThreatManager::NotifyDisengaged()
-{
-    // note: i don't really like having this here
-    // (maybe engage flag should be in creature ai? it's inherently an AI property...)
-    if (_owner->IsEngaged())
-        _owner->AtDisengage();
-}
-
 void ThreatManager::FixateTarget(Unit* target)
 {
     if (target)
@@ -530,6 +522,7 @@ void ThreatManager::UpdateVictim()
         _needClientUpdate = false;
     }
 
+    ProcessAIUpdates();
 }
 
 ThreatReference const* ThreatManager::ReselectVictim()
@@ -538,7 +531,7 @@ ThreatReference const* ThreatManager::ReselectVictim()
         return nullptr;
 
     for (auto const& pair : _myThreatListEntries)
-        pair.second->UpdateOffline();
+        pair.second->UpdateOffline(); // AI notifies are processed in ::UpdateVictim caller
 
     // fixated target is always preferred
     if (_fixateRef && _fixateRef->IsAvailable())
@@ -587,6 +580,16 @@ ThreatReference const* ThreatManager::ReselectVictim()
     return nullptr;
 }
 
+void ThreatManager::ProcessAIUpdates()
+{
+    CreatureAI* ai = ASSERT_NOTNULL(_owner->ToCreature())->AI();
+    std::vector<ThreatReference const*> v(std::move(_needsAIUpdate)); // _needClientUpdate is now empty in case this triggers a recursive call
+    if (!ai)
+        return;
+    for (ThreatReference const* ref : v)
+        ai->JustStartedThreateningMe(ref->GetVictim());
+}
+
 // returns true if a is LOWER on the threat list than b
 /*static*/ bool ThreatManager::CompareReferencesLT(ThreatReference const* a, ThreatReference const* b, float aWeight)
 {
diff --git a/src/server/game/Combat/ThreatManager.h b/src/server/game/Combat/ThreatManager.h
index 6e4f20c55a9..8e722707f91 100644
--- a/src/server/game/Combat/ThreatManager.h
+++ b/src/server/game/Combat/ThreatManager.h
@@ -103,7 +103,7 @@ class TC_GAME_API ThreatManager
         bool CanHaveThreatList() const { return _ownerCanHaveThreatList; }
         // returns the current victim - this can be nullptr if owner's threat list is empty, or has only offline targets
         Unit* GetCurrentVictim();
-        Unit* GetCurrentVictim() const;
+        Unit* GetLastVictim() const;
         // returns an arbitrary non-offline victim from owner's threat list if one exists, nullptr otherwise
         Unit* GetAnyTarget() const;
 
@@ -121,10 +121,10 @@ class TC_GAME_API ThreatManager
         Trinity::IteratorPair<ThreatListIterator> GetUnsortedThreatList() const { return { _myThreatListEntries.begin(), _myThreatListEntries.end() }; }
         // slightly slower than GetUnsorted, but, well...sorted - only use it if you need the sorted property, of course
         // this iterator pair will invalidate on any modification (even indirect) of the threat list; spell casts and similar can all induce this!
-        // note: current tank is NOT guaranteed to be the first entry in this list - check GetCurrentVictim separately if you want that!
+        // note: current tank is NOT guaranteed to be the first entry in this list - check GetLastVictim separately if you want that!
         Trinity::IteratorPair<threat_list_heap::ordered_iterator> GetSortedThreatList() const { return { _sortedThreatList.ordered_begin(), _sortedThreatList.ordered_end() }; }
         // slowest of the three threat list getters (by far), but lets you modify the threat references - this is also sorted
-        std::vector<ThreatReference*> GetModifiableThreatList() const;
+        std::vector<ThreatReference*> GetModifiableThreatList();
 
         // does any unit have a threat list entry with victim == this.owner?
         bool IsThreateningAnyone(bool includeOffline = false) const;
@@ -154,9 +154,6 @@ class TC_GAME_API ThreatManager
         void ClearThreat(ThreatReference* ref);
         // Removes all targets from the threat list (will cause evade in UpdateVictim if called)
         void ClearAllThreat();
-        // THIS SHOULD ONLY BE CALLED FROM A CREATURE'S AI (typically in EnterEvadeMode)
-        // notify the unit that the AI has disengaged
-        void NotifyDisengaged();
 
         // Fixate on the passed target; this target will always be selected until the fixate is cleared
         // (if the target is not in the threat list, does nothing)
@@ -204,6 +201,12 @@ class TC_GAME_API ThreatManager
         threat_list_heap _sortedThreatList;
         std::unordered_map<ObjectGuid, ThreatReference*> _myThreatListEntries;
 
+        // AI notifies are delayed to ensure we are in a consistent state before we call out to arbitrary logic
+        // threat references might register themselves here when ::UpdateOffline() is called - MAKE SURE THIS IS PROCESSED JUST BEFORE YOU EXIT THREATMANAGER LOGIC
+        void ProcessAIUpdates();
+        void RegisterForAIUpdate(ThreatReference const* ref) { _needsAIUpdate.push_back(ref); }
+        std::vector<ThreatReference const*> _needsAIUpdate;
+
         // picks a new victim - called from ::Update periodically
         void UpdateVictim();
         ThreatReference const* ReselectVictim();
@@ -278,7 +281,7 @@ class TC_GAME_API ThreatReference
             _owner(reinterpret_cast<Creature*>(mgr->_owner)), _mgr(*mgr), _victim(victim),
             _baseAmount(0.0f), _tempModifier(0), _taunted(TAUNT_STATE_NONE)
         {
-            _online = ShouldBeSuppressed() ? ONLINE_STATE_SUPPRESSED : ONLINE_STATE_ONLINE;
+            _online = ONLINE_STATE_OFFLINE;
         }
 
         void UnregisterAndFree();
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index d966adbdd66..007664ec134 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -3397,6 +3397,13 @@ bool Creature::CanGiveExperience() const
         && !(GetCreatureTemplate()->flags_extra & CREATURE_FLAG_EXTRA_NO_XP_AT_KILL);
 }
 
+bool Creature::IsEngaged() const
+{
+    if (CreatureAI const* ai = AI())
+        return ai->IsEngaged();
+    return false;
+}
+
 void Creature::AtEngage(Unit* target)
 {
     Unit::AtEngage(target);
diff --git a/src/server/game/Entities/Creature/Creature.h b/src/server/game/Entities/Creature/Creature.h
index 119408a2f2e..a13dff72238 100644
--- a/src/server/game/Entities/Creature/Creature.h
+++ b/src/server/game/Entities/Creature/Creature.h
@@ -367,6 +367,7 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
 
         bool CanGiveExperience() const;
 
+        bool IsEngaged() const override;
         void AtEngage(Unit* target) override;
         void AtDisengage() override;
 
diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index cb059be8d7a..2b1dbfdf74e 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/src/server/game/Entities/Unit/Unit.cpp
@@ -304,7 +304,7 @@ Unit::Unit(bool isWorldObject) :
     m_removedAurasCount(0), m_interruptMask(SpellAuraInterruptFlags::None), m_interruptMask2(SpellAuraInterruptFlags2::None),
     m_unitMovedByMe(nullptr), m_playerMovingMe(nullptr), m_charmer(nullptr), m_charmed(nullptr),
     i_motionMaster(new MotionMaster(this)), m_regenTimer(0), m_vehicle(nullptr),
-    m_vehicleKit(nullptr), m_unitTypeMask(UNIT_MASK_NONE), m_Diminishing(), m_isEngaged(false), m_combatManager(this),
+    m_vehicleKit(nullptr), m_unitTypeMask(UNIT_MASK_NONE), m_Diminishing(), m_combatManager(this),
     m_threatManager(this), m_aiLocked(false), _playHoverAnim(false), _aiAnimKitId(0), _movementAnimKitId(0), _meleeAnimKitId(0),
     _spellHistory(new SpellHistory(this))
 {
diff --git a/src/server/game/Entities/Unit/Unit.h b/src/server/game/Entities/Unit/Unit.h
index e42cce1e913..e88bcf953eb 100644
--- a/src/server/game/Entities/Unit/Unit.h
+++ b/src/server/game/Entities/Unit/Unit.h
@@ -1099,10 +1099,10 @@ class TC_GAME_API Unit : public WorldObject
 
         /// ====================== THREAT & COMBAT ====================
         bool CanHaveThreatList() const { return m_threatManager.CanHaveThreatList(); }
-        // This value can be different from IsInCombat:
+        // This value can be different from IsInCombat, for example:
         // - when a projectile spell is midair against a creature (combat on launch - threat+aggro on impact)
         // - when the creature has no targets left, but the AI has not yet ceased engaged logic
-        bool IsEngaged() const { return m_isEngaged; }
+        virtual bool IsEngaged() const { return IsInCombat(); }
         bool IsEngagedBy(Unit const* who) const { return CanHaveThreatList() ? IsThreatenedBy(who) : IsInCombatWith(who); }
         void EngageWithTarget(Unit* who); // Adds target to threat list if applicable, otherwise just sets combat state
         // Combat handling
@@ -1938,11 +1938,12 @@ class TC_GAME_API Unit : public WorldObject
         virtual void ProcessTerrainStatusUpdate(ZLiquidStatus status, Optional<LiquidData> const& liquidData);
         virtual void SetInWater(bool inWater);
 
+        // notifiers
         virtual void AtEnterCombat();
         virtual void AtExitCombat();
 
-        virtual void AtEngage(Unit* /*target*/) { m_isEngaged = true; }
-        virtual void AtDisengage() { m_isEngaged = false; }
+        virtual void AtEngage(Unit* /*target*/) {}
+        virtual void AtDisengage() {}
 
     private:
 
@@ -1971,7 +1972,6 @@ class TC_GAME_API Unit : public WorldObject
         Diminishing m_Diminishing;
 
         // Threat+combat management
-        bool m_isEngaged;
         friend class CombatManager;
         CombatManager m_combatManager;
         friend class ThreatManager;