He attacks by hurling explosive lava bombs (which, on Hard difficulty, are aimed ahead of moving targets).
He resides in a pool of lava, emerging once you pick up the episode's rune. You can find him in The House of Chthon, which is preceded by The Door to Chthon. † The data files for monsters that appear only in the registered version of Quake reside in pak1.pak rather than pak0.pak.Ĭhthon is the end boss of the first episode, Dimension of the Doomed.