Chzo is the last pain elemental that lives in the World of Magick. As a pain elemental, he feeds on the agony that others feel. He is not above capturing those who stray into his territory in order to torture them and squeeze out every last drop of pain.
Chzo became the most powerful pain elemental at some point in the distant past, by defeating and absorbing all of his rivals. This made him a literal mountain of flesh, that needs to feed on huge amounts of magick and pain in order to stay alive.