Tharizdun

, the Chained Oblivion, is the mad deity of death and trickery. It is depicted, if at all, as "a creature of rolling, hungry ink and darkness".

Tharizdun was released onto the Material Plane during the Calamity, causing untold destruction and chaos. It was responsible for dealing a great wound to Ioun, from which she is still recovering.

The Rites of Prime Banishment were used for the first time to re-banish Tharizdun and end the war of the Calamity. During these rites, it took Pelor's full might to beat down Tharizdun, attach four Prime Trammels, and finally complete the ritual. Tharizdun was, however, successfully banished.