Fan Casting Metallo in Superman

John Corben, an inmate who suffers from a debilitating heart condition, is selected by Lex Luthor and Winslow Schott to be their guinea pig in taking down Superman. Having served time in prison for mass murder, John is brought in to LexCorp where he is given the deal to cure his disease and also to become a weapon of war. Corben accepts, with Schott transforming him into Metallo, a cyborg almost completely comprised of machine technology that is fueled by a Kryptonite power source.