Scripts/VioletHold: rewrote the whole instance

thanks @MitchesD for help

src/server/game/AI/ScriptedAI/ScriptedCreature.cpp

@@ -457,7 +457,13 @@ BossAI::BossAI(Creature* creature, uint32 bossId) : ScriptedAI(creature),
     instance(creature->GetInstanceScript()),
     summons(creature),
     _boundary(instance ? instance->GetBossBoundary(bossId) : NULL),
-    _bossId(bossId) { }
+    _bossId(bossId)
+{
+    scheduler.SetValidator([this]
+    {
+        return !me->HasUnitState(UNIT_STATE_CASTING);
+    });
+}
 
 void BossAI::_Reset()
 {
@@ -467,6 +473,7 @@ void BossAI::_Reset()
     me->ResetLootMode();
     events.Reset();
     summons.DespawnAll();
+    scheduler.CancelAll();
     if (instance)
         instance->SetBossState(_bossId, NOT_STARTED);
 }
@@ -475,14 +482,13 @@ void BossAI::_JustDied()
 {
     events.Reset();
     summons.DespawnAll();
+    scheduler.CancelAll();
     if (instance)
         instance->SetBossState(_bossId, DONE);
 }
 
 void BossAI::_EnterCombat()
 {
-    me->setActive(true);
-    DoZoneInCombat();
     if (instance)
     {
         // bosses do not respawn, check only on enter combat
@@ -493,6 +499,10 @@ void BossAI::_EnterCombat()
         }
         instance->SetBossState(_bossId, IN_PROGRESS);
     }
+
+    me->setActive(true);
+    DoZoneInCombat();
+    ScheduleTasks();
 }
 
 void BossAI::TeleportCheaters()