Mastermind affected a huge scale that sometimes even fooled some telepaths. Mastermind started out pretty much a wimp, but Empath remained this way for much of his own tenure (i.e. fainted when Wolverine drew out his claws in front of his face). Mastermind is superior here.
i would have the join the band waggon and say mastermind. i mean mastermind was able to break down jeans mental blocks turning her into dark phoenix he could wipe the floor with empath
Emma created a device that complimented Mastermind to engage his target on a level that could rival a standard telepath, which enabled him to almost control Phoenix and of course, nearly kill Cyclops in a illusionary duel.
So could Mastermind kill someone using his powers? I mean could he have them thinking that they are drowning or burning alive and they really died from like exhaustion or shock? That would be interesting...anyway Mastermind wins...