Ben 10: Ultimate Alien Episode 1.07 Andreas' Fault

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. As a last act of spite, their leader sets a bomb that will destroy everything within five miles. Andreas sacrifices himself to absorb the force of the explosion. Although Ben and company believe him to be dead, Andreas survives and is found by Aggregor.