Added GroupAIFlags Based on TrinityCore

Framework/Constants/CreatureConst.cs

@@ -335,4 +335,12 @@ namespace Framework.Constants
         SequenceBreak,    // this is a boss and the pre-requisite encounters for engaging it are not defeated yet
         Other
     }
+
+    public enum GroupAIFlags
+    {
+        None = 0,          // If any creature from group is attacked, members won't assist and won't follow
+        LeaderAggro = 0x00000001, // The member aggroes if the leader aggroes
+        MemberAggro = 0x00000002, // The leader aggroes if the member aggroes
+        Follow = 0x00000004, // The member will follow the leader
+    }
 }

Game/Entities/Creature/CreatureGroups.cs

@@ -19,6 +19,7 @@ using Framework.Database;
 using Game.Maps;
 using System;
 using System.Collections.Generic;
+using Framework.Constants;
 
 namespace Game.Entities
 {
@@ -173,13 +174,10 @@ namespace Game.Entities
 
         public void MemberAttackStart(Creature member, Unit target)
         {
-            byte groupAI = FormationMgr.CreatureGroupMap[member.GetSpawnId()].groupAI;
+            GroupAIFlags groupAI = (GroupAIFlags)FormationMgr.CreatureGroupMap[member.GetSpawnId()].groupAI;
             if (groupAI == 0)
                 return;
 
-            if (groupAI == 1 && member != m_leader)
-                return;
-
             foreach (var pair in m_members)
             {
                 if (m_leader) // avoid crash if leader was killed and reset.
@@ -197,7 +195,7 @@ namespace Game.Entities
                 if (other.GetVictim())
                     continue;
 
-                if (other.IsValidAttackTarget(target))
+                if (((other != m_leader && groupAI.HasAnyFlag(GroupAIFlags.LeaderAggro)) || (other == m_leader && groupAI.HasAnyFlag(GroupAIFlags.MemberAggro))) && other.IsValidAttackTarget(target))
                     other.GetAI().AttackStart(target);
             }
         }
@@ -230,7 +228,8 @@ namespace Game.Entities
             foreach (var pair in m_members)
             {
                 Creature member = pair.Key;
-                if (member == m_leader || !member.IsAlive() || member.GetVictim())
+                GroupAIFlags groupAI = (GroupAIFlags)FormationMgr.CreatureGroupMap[member.GetSpawnId()].groupAI;
+                if (member == m_leader || !member.IsAlive() || member.GetVictim() || !groupAI.HasAnyFlag(GroupAIFlags.Follow))
                     continue;
 
                 if (pair.Value.point_1 != 0)

Game/Entities/Unit/Unit.Spells.cs

@@ -4123,9 +4123,9 @@ namespace Game.Entities
             }
 
             uint spellId = aura.GetId();
-            var range = m_ownedAuras.Where(p => p.Key == spellId);
 
-            foreach (var pair in range)
+            var range = m_ownedAuras.Where(p => p.Key == spellId);
+            foreach (var pair in range.ToList())
             {
                 if (pair.Value == aura)
                 {
@@ -4235,9 +4235,9 @@ namespace Game.Entities
                 return;
 
             uint spellId = aurApp.GetBase().GetId();
-            var range = m_appliedAuras.Where(p => p.Key == spellId);
 
-            foreach (var pair in range)
+            var range = m_appliedAuras.Where(p => p.Key == spellId);
+            foreach (var pair in range.ToList())
             {
                 if (aurApp == pair.Value)
                 {