Halaster Blackcloak is a powerful and enigmatic wizard from the Dungeons & Dragons universe, particularly known for his role in the Forgotten Realms campaign setting. He is the creator of the Undermountain, a vast and dangerous dungeon located beneath the city of Waterdeep. Halaster is often depicted as a master of arcane magic, having achieved great power through his extensive studies and experiments. Originally a mortal man, Halaster's quest for knowledge led him to become a lich, granting him immortality at the cost of his humanity. His obsession with magic and control over the Undermountain has made him a central figure in many adventures, as adventurers seek to uncover the secrets of his domain and confront the challenges he has left behind.