The mutant is granted magical powers. It receives one Magic level, plus the associated spells (determined randomly or chosen from any list), magic points and power level.
If the mutant is Mindless or Moronic, it still receives its magical powers, but it may not be capable of using them! The mutant's Chaos Power just happened to be in a humourous, if fickle, mood.
Followers of Khorne can receive these magical powers, but their use earns Khorne's great disfavour.