Superdoom was a corrupt version of Superman from an alternate universe. Superdoom was also the main champion of Vyndktvx and appeared to be a mix between Superman and Doomsday. On Prime Earth, when Superman was infected by the Doomsday Virus and began to merge with Doomsday, he was referred to as Superdoom.
Created by a solid thought machine, Superdoom was stolen by Vyndktvx and taken to an alternate universe. There Superdoom gained a hatred for Superman and Lex Luthor. When finally taken to confront the Superman Vyndktvx hated, it took the efforts of everybody on Earth to stop Superdoom. The attack of Superdoom was reminiscient to that of Doomsday.