When a horde of supervillains attack Metropolis, heroes, current and retired, fly off to the rescue, and they are joined by the National Guard. The battle results in multiple deaths on both sides, including many by Superboy-Prime himself, who kills villains and heroes alike. During the battle, Superboy-Prime takes off to destroy Oa, planning to collapse the Universe in a big bang event, and recreate it with himself as the only superhero. Superboy-Prime is slowed down by a 300-mile thick wall of willpower created by the Green Lantern Corps, but he kills thirty-two Green Lanterns before Kal-L and Kal-El carry him toward what is left of Krypton. It is essentially a huge cloud of kryptonite. The Supermen fly Superboy through Krypton's red sun, Rao, destroying his armor and causing all three Kryptonians' powers to diminish. Falling to the sentient planet (and Green Lantern Corps member) Mogo, they fight. Kal-El finally knocks Superboy-Prime out and the older Superman Kal-L dies of his injuries in the arms of his cousin, Power Girl.