BackStory
Little is known about this supervillain character profile, and unfortunately it will probably remain that way until the Mastermind allows us, or rather wants us, to learn more.
Affiliations
The Mastermind runs a top-secret organization known as the Legion of the Mind. There he experiments on superheroes that he has captured in order to learn about them, study their abilities, and replicate their powers into his own cruel, twisted creations.
No hero has been able to best the Mastermind. When they think they've won, at the last second one of the Mastermind's contingency plans kicks in, rendering the hero completely vulnerable to defeat.
The Mastermind is somewhat analogous to a great chess player who allows you to believe you're winning, sacrificing his queen just to prove his superior intellect by claiming victory with an unexpected rook.
Powers & Abilities
The Mastermind has no powers per se aside from his insane intellect, but even his intelligence wasn't always this way. The Mastermind was brilliant, exceptionally gifted with an extremely high IQ, but it took the manipulations of his brain from outside means to make him something more, something inevitable, something seemingly omniscient.
The Mastermind's energy power scale factor is due to his use of highly explosive bombs that he deploys (which make atomic weapons look like child's play). For his weaponry, he prefers something of the more antimatter-like variety. As for the Mastermind's extremely high psionic scores, that derives from his technology as well, in which he has devised a force field-creating device. This device forms a field around his body and scheming room, making both of them nearly indestructible.