C’th the Undying is a fairly powerful sorcerer that uses Earth magic.
He was originally worshipped as a god, but his people drive him out. He tried to find new followers in Britain and America, to no avail. He was imprisoned for two thousand years before finally awakening in our time.
He is raised up by Klarion to join a gang dedicated to defeating Etrigan. He also unsuccessfully tries to make Glenda his bride.
C’th uses a magical crystal bone to focus his magical energy blasts.
Lobo kills him by blasting his head off with a tank.