npc_sk_undying_shadows(Creature* cre) : ScriptedAI(cre)
    {
        instance = me->GetInstanceScript();
        me->SetReactState(REACT_PASSIVE);
    }

    ObjectGuid fixateGuid;
    InstanceScript* instance;
    uint32 checkTimer = 0;
    bool isDead = false;

    void IsSummonedBy(Unit* summoner) override
    {
        if (instance->GetBossState(DATA_SPIRIT_KINGS) != IN_PROGRESS)
        {
            me->DespawnOrUnsummon(500);
            return;
        }

        if (summoner && summoner->isAlive())
        {
            fixateGuid = summoner->GetGUID();
            me->AddAura(SPELL_UNDYING_SHADOWS_FIXATE, summoner);
        }

        checkTimer = 500;
        DoCast(me, SPELL_UNDYING_SHADOWS_VISUAL_IS_ALIVE, true);
    }

    void SpellHitTarget(Unit* target, const SpellInfo* spell) override
    {
        if (target && spell->Id == SPELL_UNDYING_SHADOWS_FIXATE)
            fixateGuid = target->GetGUID();
    }

    void DamageTaken(Unit* attacker, uint32& damage) override
    {
        if (damage >= me->GetHealth())
        {
            damage = 0;

            if (!isDead)
            {
                isDead = true;

                if (auto plr = me->GetPlayer(*me, fixateGuid))
                    plr->RemoveAura(SPELL_UNDYING_SHADOWS_FIXATE);

                me->SetHealth(1);
                me->RemoveAura(SPELL_UNDYING_SHADOWS_VISUAL_IS_ALIVE);
                me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE | UNIT_FLAG_NOT_SELECTABLE);
                me->GetMotionMaster()->Clear();

                me->AddDelayedEvent(500, [=]()-> void
                {
                    DoCast(me, SPELL_UNDYING_SHADOWS_VISUAL_IS_DEAD, true);
                    DoCast(me, SPELL_COALESCING_SHADOWS, true);
                    DoCast(me, SPELL_SHRINK_STACKER, true);
                });
            }
        }
    }

    void UpdateAI(uint32 diff) override
    {
        if (checkTimer)
            if (checkTimer <= diff)
            {
                if (instance->GetBossState(DATA_SPIRIT_KINGS) == IN_PROGRESS)
                {
                    checkTimer = 500;

                    if (!isDead)
                    {
                        auto plr = me->GetPlayer(*me, fixateGuid);

                        if (!plr || !plr->isAlive() || !plr->HasAura(SPELL_UNDYING_SHADOWS_FIXATE))
                        {
                            checkTimer = 1000;
                            DoCast(me, SPELL_UNDYING_SHADOWS_FIXATE, true);
                        }
                        else
                            me->GetMotionMaster()->MovePoint(1, plr->GetPosition(), false);
                    }
                }
                else
                {
                    checkTimer = 0;
                    me->DespawnOrUnsummon(500);
                }
            }
            else
                checkTimer -= diff;
    }