When the space pirate Nebula destroyed the planet Xandar, its World-Mind transferred the deceased Nova Corps’ collective Nova-Force into their sole survivor, Garthan Saal, to safeguard the energies and distribute them to worthy successors of Xandar’s noble tradition. Saal was transformed into the immensely powerful Super-Nova, but the energies drove him mad. Seeking vengeance on Nebula, Saal beat the similarly searching Starfox and Firelord (a fellow Xandarian) when they could not deliver her. Saal learned that Nebula was involved with Earth’s Avengers – though neither Saal nor the Avengers realized this was Ravonna, the future Terminatrix, impersonating Nebula – and he prepared to destroy Earth unless he received Nebula. Saal withstood the combined assaults of Quasar, the Fantastic Four, and the Avengers, but Reed Richards convinced him to enter the timestream to pursue the timelost Nebula.
His search fruitless, Saal watched with rage as the human Richard Rider regained his Nova-Power. Saal returned to Earth, and the coming together of all portions of the Nova-Force in the universe activated a failsafe in the World-Mind, cloning Xandar’s Queen Adora. Saal defeated Nova (Rider) and forced him to surrender his power, then learned that Rider was also imbued with Xandar’s spirit. He combined his power with Rider to restore Xandar, but Rider absorbed Saal’s power instead. Saal fell comatose while Rider restored Xandar’s World-Mind and was instated as Nova Centurion Prime. Recovering, Saal was made Centurion Sector Coordinator, but after Rider refused an order to assist the reformed Nova Corps (a.k.a. StarCorp), Adora – apparently pressured by Shi’ar representatives – sent Saal, as Nova Omega, to strip Rider of rank and power. Rider fled to Adora to learn the truth, and she confirmed Saal’s replacing him as Centurion Prime. Saal accompanied Rider to Earth, but their pilot revealed himself to be Volx the Dire Wraith Queen. The ship crashed on Earth, and Volx escaped when Rider spitefully shot Saal with a blaster. Volx captured the pursuing Saal and drained his energy to power a doomsday weapon, but Rider and the New Warriors freed Saal, who joined Rider in exploding Volx’s base.
Stationed in Earth’s orbit, Saal enjoyed his new mission, becoming a local hero in San Francisco and remotely communicating with old friend Mexxa Rien. After assisting the Warriors against the Sphinx and preventing a disastrous radiation release, Saal learned his superiors were spying on Earth. Cutting their connection, Saal helped the Warriors locate Volx, who was arranging to remove Earth’s superhumans’ powers. Volx seemed unbeatable until Saal tried to drain her power. The vast energies mortally wounded Saal, but this left Volx weakened. Dying, Saal returned Rider’s power and informed him of Xandar’s treachery. The Warriors slew Volx, and Saal’s brain patterns were presumably transferred to the World-Mind, living on in Richard Rider to this day.