Sometimes madness slips between the ropes

A boxer loses the biggest fight of his life. He slowly finds himself, giving up his dream and finds that life is not worth living. At least, those lives around him are not worthy of life. He steps through and unleashes an entity that torments him and guile's him to do unspeakable acts of torture and murder. As body counts rise and lives are diminished, will he have any hope? Any way to fight back to what he once was? 

Region 1