Bist was highly deceptive and utterly selfish.
Bist, like all archdevils, had a number of natural magical powers she could use at will. Additionally, she was immune to all mind-effecting spells (including charms, hold monster, and sleep). She could only be injured by powerfully enchanted weapons. Bist also possessed the normal abilities of a hellcat.
Bist was confined and forced to wander the plane of Avernus.
Bist was exiled for her duplicitous and self-centered nature. Additionally, her name was changed to prevent her from leaving Baator by way of summoning spells.