Anguished Souls are spirits found in The Ebony Citadel of Mallyx, bound by Mallyx to serve him. There are four types. Each of them causes a different Environment Effect:
10 Listless Soul
10 Tormented Soul
10 Demonic Soul
10 Shrouded Soul
Killing the spirit removes the respective effect, but the spirit may be resurrected by the Unyielding Anguish monster skill.