5 files changed, 47 insertions, 2 deletions

diff --git a/src/server/game/AI/CreatureAI.cpp b/src/server/game/AI/CreatureAI.cpp
index 9130e10bf13..a31455d5c09 100644
--- a/src/server/game/AI/CreatureAI.cpp
+++ b/src/server/game/AI/CreatureAI.cpp
@@ -124,7 +124,7 @@ void CreatureAI::MoveInLineOfSight(Unit* who)
     if (me->IsEngaged())
         return;
 
-    if (me->HasReactState(REACT_AGGRESSIVE) && me->CanStartAttack(who, false))
+    if (me->HasReactState(REACT_AGGRESSIVE) && me->CanStartAttack(who, false) && (me->IsAggroGracePeriodExpired() || me->GetMap()->Instanceable()))
         me->EngageWithTarget(who);
 }
 
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index 0a5c0c88612..466ddec3800 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -315,7 +315,7 @@ Creature::Creature(bool isWorldObject) : Unit(isWorldObject), MapObject(), m_Pla
     m_AlreadyCallAssistance(false), m_AlreadySearchedAssistance(false), m_cannotReachTarget(false), m_cannotReachTimer(0),
     m_meleeDamageSchoolMask(SPELL_SCHOOL_MASK_NORMAL), m_originalEntry(0), m_homePosition(), m_transportHomePosition(),
     m_creatureInfo(nullptr), m_creatureData(nullptr), m_creatureDifficulty(nullptr), m_stringIds(), _waypointPathId(0), _currentWaypointNodeInfo(0, 0),
-    m_formation(nullptr), m_triggerJustAppeared(true), m_respawnCompatibilityMode(false), _lastDamagedTime(0),
+    m_formation(nullptr), m_triggerJustAppeared(true), m_respawnCompatibilityMode(false), _aggroGracePeriodExpired(false), _lastDamagedTime(0),
     _regenerateHealth(true), _creatureImmunitiesId(0), _gossipMenuId(0), _sparringHealthPct(0)
 {
     m_regenTimer = CREATURE_REGEN_INTERVAL;
@@ -929,6 +929,16 @@ void Creature::Heartbeat()
 
     // Creatures with CREATURE_STATIC_FLAG_2_FORCE_PARTY_MEMBERS_INTO_COMBAT periodically force party members into combat
     ForcePartyMembersIntoCombat();
+
+    // creatures should only attack surroundings initially after heartbeat has passed or until attacked
+    if (!_aggroGracePeriodExpired)
+    {
+        _aggroGracePeriodExpired = true;
+
+        // trigger MoveInLineOfSight
+        Trinity::CreatureAggroGracePeriodExpiredNotifier notifier(*this);
+        Cell::VisitAllObjects(this, notifier, GetVisibilityRange());
+    }
 }
 
 void Creature::Regenerate(Powers power)
@@ -2335,6 +2345,7 @@ void Creature::Respawn(bool force)
                 ai->Reset();
 
             m_triggerJustAppeared = true;
+            _aggroGracePeriodExpired = false;
 
             uint32 poolid = GetCreatureData() ? GetCreatureData()->poolId : 0;
             if (poolid)
@@ -3672,6 +3683,8 @@ void Creature::AtEngage(Unit* target)
 {
     Unit::AtEngage(target);
 
+    _aggroGracePeriodExpired = true;
+
     GetThreatManager().ResetUpdateTimer();
 
     if (!HasFlag(CREATURE_STATIC_FLAG_2_ALLOW_MOUNTED_COMBAT))
diff --git a/src/server/game/Entities/Creature/Creature.h b/src/server/game/Entities/Creature/Creature.h
index a7f6113aab6..7bf4560e4e4 100644
--- a/src/server/game/Entities/Creature/Creature.h
+++ b/src/server/game/Entities/Creature/Creature.h
@@ -455,6 +455,8 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
         void SetNoThreatFeedback(bool noThreatFeedback) { _staticFlags.ApplyFlag(CREATURE_STATIC_FLAG_3_NO_THREAT_FEEDBACK, noThreatFeedback); }
         void ForcePartyMembersIntoCombat();
 
+        bool IsAggroGracePeriodExpired() { return _aggroGracePeriodExpired; }
+
         void OverrideSparringHealthPct(float healthPct) { _sparringHealthPct = healthPct; }
         void OverrideSparringHealthPct(std::vector<float> const& healthPct);
         float GetSparringHealthPct() const { return _sparringHealthPct; }
@@ -579,6 +581,8 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
         bool m_triggerJustAppeared;
         bool m_respawnCompatibilityMode;
 
+        bool _aggroGracePeriodExpired;
+
         /* Spell focus system */
         void ReacquireSpellFocusTarget();
         struct
diff --git a/src/server/game/Grids/Notifiers/GridNotifiers.cpp b/src/server/game/Grids/Notifiers/GridNotifiers.cpp
index 067898f671b..f004e15b564 100644
--- a/src/server/game/Grids/Notifiers/GridNotifiers.cpp
+++ b/src/server/game/Grids/Notifiers/GridNotifiers.cpp
@@ -242,6 +242,25 @@ void AIRelocationNotifier::Visit(CreatureMapType &m)
     }
 }
 
+void CreatureAggroGracePeriodExpiredNotifier::Visit(CreatureMapType& m)
+{
+    for (CreatureMapType::iterator iter = m.begin(); iter != m.end(); ++iter)
+    {
+        Creature* c = iter->GetSource();
+        CreatureUnitRelocationWorker(c, &i_creature);
+        CreatureUnitRelocationWorker(&i_creature, c);
+    }
+}
+
+void CreatureAggroGracePeriodExpiredNotifier::Visit(PlayerMapType& m)
+{
+    for (PlayerMapType::iterator iter = m.begin(); iter != m.end(); ++iter)
+    {
+        Player* player = iter->GetSource();
+        CreatureUnitRelocationWorker(&i_creature, player);
+    }
+}
+
 /*
 void
 MessageDistDeliverer::VisitObject(Player* player)
diff --git a/src/server/game/Grids/Notifiers/GridNotifiers.h b/src/server/game/Grids/Notifiers/GridNotifiers.h
index 1abf2c06d96..fe62b36225d 100644
--- a/src/server/game/Grids/Notifiers/GridNotifiers.h
+++ b/src/server/game/Grids/Notifiers/GridNotifiers.h
@@ -108,6 +108,15 @@ namespace Trinity
         void Visit(CreatureMapType &);
     };
 
+    struct TC_GAME_API CreatureAggroGracePeriodExpiredNotifier
+    {
+        Creature& i_creature;
+        CreatureAggroGracePeriodExpiredNotifier(Creature& c) : i_creature(c) { }
+        template<class T> void Visit(GridRefManager<T>&) { }
+        void Visit(CreatureMapType&);
+        void Visit(PlayerMapType&);
+    };
+
     struct GridUpdater
     {
         GridType &i_grid;