Over time, most of Malus's fellow duergar went mad as a result of the influence of the Seed of Fel Earth, a sentient stone part of Ogrémoch. Malus's cleric powers protected him but, circa 1486 DR, the seed directed against him a purple worm and in the battle they slew each other. Malus however rose again as a specter.
As a specter, Malus had a mental connection to the seed that tormented him. He felt as though he was a germ trapped inside a great restless beast and he felt all of its pain. He frequently rambled his lamentations and was prone to violent outbursts.