fix(Scripts/AN): Ensure only the watchers minions start the event (#24371)

src/server/scripts/Northrend/AzjolNerub/AzjolNerub/instance_azjol_nerub.cpp

@@ -118,23 +118,42 @@ public:
 
         void OnUnitDeath(Unit* unit) override
         {
-            if (unit->EntryEquals(NPC_WATCHER_GASHRA, NPC_WATCHER_NARJIL, NPC_WATCHER_SILTHIK, NPC_ANUBAR_SHADOWCASTER, NPC_ANUBAR_SKIRMISHER, NPC_ANUBAR_WARRIOR))
+            if (!unit->EntryEquals(NPC_WATCHER_GASHRA, NPC_WATCHER_NARJIL, NPC_WATCHER_SILTHIK, NPC_ANUBAR_SHADOWCASTER, NPC_ANUBAR_SKIRMISHER, NPC_ANUBAR_WARRIOR))
-            {
+                return;
-                if (Creature* creature = unit->ToCreature())
+
+            Creature* creature = unit->ToCreature();
+            if (!creature)
+                return;
+
+            // For trash mobs, ensure their leader is a Watcher
+            if (unit->EntryEquals(NPC_ANUBAR_SHADOWCASTER, NPC_ANUBAR_SKIRMISHER, NPC_ANUBAR_WARRIOR))
             {
+                CreatureGroup* formation = creature->GetFormation();
+                if (!formation)
+                    return;
+
+                Creature* leader = formation->GetLeader();
+                if (!leader || !leader->EntryEquals(NPC_WATCHER_GASHRA, NPC_WATCHER_NARJIL, NPC_WATCHER_SILTHIK))
+                    return;
+            }
+
             ObjectGuid creatureGuid = creature->GetGUID();
+
             scheduler.CancelAll();
             scheduler.Schedule(1s, [this, creatureGuid](TaskContext /*context*/)
             {
-                        if (Creature* creature = instance->GetCreature(creatureGuid))
+                Creature* creature = instance->GetCreature(creatureGuid);
-                            if (CreatureGroup* formation = creature->GetFormation())
+                if (!creature)
-                                if (!formation->IsAnyMemberAlive())
+                    return;
+
+                CreatureGroup* formation = creature->GetFormation();
+                if (!formation || formation->IsAnyMemberAlive())
+                    return;
+
                 if (Creature* krikthir = GetCreature(DATA_KRIKTHIR))
                     krikthir->AI()->DoAction(ACTION_MINION_DIED);
             });
         }
-            }
-        }
     };
 
     InstanceScript* GetInstanceScript(InstanceMap* map) const override