Phlegethos

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun The most infernal region of the Nine Hells, in the classical sense. It is a plane of nightmare, with active volcanoes, flowing lava, and rivers of elemental fire. Those who are not protected in this violent land can expect to suffer a flaming death. Belial rules this plane from the depths of the palace of Abriymoch, built into the heart of a gigantic but extinct volcano.