Melnrath was a alhoon, or a mind flayer lich. He ruled at a keep on the island that used to belong to the Defenders of Illian. The creature led an assault on the city of Manatheran that was successfully repelled with the assistance of our heroes. The lich was responsible for the creation of a new type of undead creatures that were capable of penetrating the defenses of the city as well as regenerating and re-assembling themselves. He was also the creator of the creature known as Patch.
He was defeated by the heroes when they met as part of an agreement that they made with the lich. He was betrayed by the nightwalker that guarded him and destroyed by the heroes.