WoWDB

Mumta resides on the top floor of the large mansion-esque building in the Court of Bones. To defeat Mumta, you must remember that you can only heal yourself when the healing debuff is not active, kite Mumta so that his summoned spirit does not catch you, and interrupt (or CC him) when he channels his spirit bolts.

Mumta's most powerful ability is undoubtedly  Spirit Bolts, which must be interrupted because it deals a total of 400k damage over the course of its 10-second channel. His oddest ability is  Darkest Darkness. It isn't a massive threat since Mumta does not hit particularly hard (as long as you interrupt his powerful ability), but most players will probably need to heal at least once during the fight, so make sure to do it when Darkest Darkness is not active. Lastly, Mumta will occasionally cast  Vengeful Spirit, which summons a Vengeful Spirit that moves very slowly towards you. When the Vengeful Spirit is active, make sure to kite Mumta around and to never enter the Vengeful Spirit's melee range because it hits exceptionally hard.