This article needs to be properly cited per Tardis:Citation.
He learned of a crashed spacecraft and found it contained four Cybermen. He took them to a secret laboratory to build more and create an army he could control, using peasant body parts. When the Sixth Doctor arrived to investigate, he faked an attack on himself to divert suspicion. The Doctor eventually found the laboratory. When Sovak tried to activate all the Cybermen, he caused a power overload which killed him and destroyed the lab. (COMIC: Revelation!, Genesis!)