Gehenna

The Broken World of Gehenna was the ninth and final layer of the Nine Hells. It was an Outer Plane also known as the Bleak Eternity, and was home to the powerful Asmodeus, leader of the Prime Evils. It was a realm of black, lightless fire, rising out of a featureless plain of jagged rock. It was said that only those with devil's sight could even perceive the true nature of the plane; others were simply rendered senseless, their bodies and souls wracked with pain and sorrow from a thousand unknown sources.