The cumulative abilities of all his personalities make him one of the most powerful mutants in existence, if not the most powerful. Since the abilities of his personalities stem from his subconscious alteration of reality, Legion is theoretically capable of manifesting any power he can imagine. In two instances David has manifested the full extent of his ability to alter time and reality: in the first, he wiped the Elder Gods from existence and reset the universe to a state before the Elder Gods first appeared on Earth, and in the other he observed the entirety of spacetime and mended damage his personalities had done to it.