You get the once in a life time chance to make a life long change to a major comic book character from whatever company you wish. You have the executive power to turn one established, previously heroic character into a villain and turn one established, previously villainous character into a hero.

These changes, btw, are permanent and will not be retconed or reversed in any way. Your new hero stays a hero, either with their own recurring title or simply as a supporting character in the pages of other titles, and so does your new villain.