Omega created the Ergon with his power of psychosynthesis. He considered it one of his less successful creations. (TV: Arc of Infinity) Bizarrely, while on Earth (presumably in Perivale, where she grew up), Ace saw it while working at a fast food restaurant. Ace, at the time, mistook it for a person wearing a costume. (PROSE: Anti-Matter with Fries) It used a matter converter, with which it shot Colin Frazer, Tegan Jovanka and Robin Stuart. While the Fifth Doctor wrestled with the Ergon, Nyssa took its gun and shot it. (TV: Arc of Infinity)