Mist Master was a member of Superboy-Prime’s Legion of Super-Villains, when they fought members of the Legion of Super-Heroes of three universes. He apparently survived the encounter. Notably, it appears that Mist Master now remains in gaseous form at all times, and no longer bothers to revert to human form. His earlier history can be assumed to be the same as, or similar to, that of his Pre-Zero Hour counterpart.