Maphas-Kas is a huge crater that came about when an ancient volcano collapsed upon itself. Maphas-Kas is a jungle-filled area with numerous streams that all end up in the deep waters of Agûrbâte. Those streams that begin in Mulun'nâth are sickly color and often toxic. Perched on the western rim of the crater is the capital of the Black Tide, the great undead city Phanêthil.
Some of the most numerous predators of this crater are of course undead, along with blood apes and grell.