Aec'Letec

Aec'Letec was a powerful tanar'ri that was killed by Durlag Trollkiller who then trapped the demon's soul in an enchanted dagger. Eventually after the madness and the death of Durlag, Aec'Letec broke free from the dagger but remained trapped in Durlag's Tower. At last, Gorion's Ward entered the tower and, on the highest floor, fought and killed the demon.