Halaster Blackcloak was a notorious, ancient, and utterly insane wizard who resided within his lair, the infamous Undermountain. As a mighty archmage, Halaster Blackcloak had a vast array of spells and magical powers at his command. Among them, he could make use of contingency spells and clones of himself to ensure his survival in any spell-battle. Inside Undermountain, he could command all kinds of constructs, including crawling claws, helmed horrors, and various golems. He also made use of its countless traps and and surprises, such as a moving portal that could pick up either himself or his victims and deposit them somewhere else. In addition to his great magical prowess, Halaster was well-versed in many areas, from gem-cutting to engineering to the breeding, care, and containment of monsters, both alive and undead, particularly from those hailing from other planes.