Ben 10: Ultimate Alien - Season 1 Episode 7

When Ben, Kevin, and Gwen investigate an odd string of thefts by the Forever Knights, they learn that Argit is using Andreas (one of the aliens being hunted by Aggregor) to frighten them into making him their leader. Argit's plans go bad when the Forever Knights eventually revolt, and throw him into a dungeon with Ben and the others. When they discover that the Knights plan to execute Andreas, they break out and save him. But when a Forever Knight sets a bomb that would level the entire castle, Andreas sacrifices himself to absorb the force of the explosion. Although Ben and company believed him to be dead, Andreas survived the explosion. Unfortunately, the endeavor of stopping the bomb made him too weak to resist Aggregor as he recaptures him.