The DC Comics Earth was saved by Superman and... The Joker?

Certain things are guaranteed in comic books. Spider-Man can’t be happy, Wonder Woman is not to be messed with, and Joker's mind is underrated. The latter remained the same despite being infected with a spell conjured by (of all people) Bizarro.

At the end of Action Comics No. 1062, Superman lost his battle with Bizarro’s spell and was the last normal person on Earth. Even Batman and Wonder Woman were corrupted. No matter how powerful Superman is, he can't beat the world. The only way to win was to find Bizarro No. 1 (who was trapped inside Kal-El's mind). To do that, he enlisted the help of the Clown Prince of Crime.

The Bizarro spell affected Joker like everyone else. The difference was he was bizarre before the magic infected Earth. Instead, the spell made him calm and empathetic. Two things Superman needed.

When Bizarro defeated Superman, Joker spoke to him. He tells Bizarro his hopes, dreams, regrets, and more. As the narrator put it, “He (Joker) speaks in truths so stark and pure that Bizarro is left trembling from the mere act of hearing them so bravely and boldly uttered aloud.” The best part is readers find out that Joker wasn’t speaking to Bizarro. He was talking to Superman who was trapped in Bizarro’s mind.

Eventually, Superman regains control and knows how to reverse the spell. Before doing so, he tells Joker that he’ll go back to the way he was. Joker says he always knew. Superman thanks him and Joker says, “It’s been an honor.” Kal-El unleashes the cure and reverses the Bizarro spell. Joker leaves Superman a message on the Daily Planet globe saying, "I'd rather be crazy in Gotham than sane in..."

Like most comic books, this isn’t the end. No one has seen Bizarro No. 1 since the incident.  However, Superman says that he can hear Bizarro inside him growing, “Be Bizarro.” For now, Kal-El can contain the voices and impulses. But readers know this won’t last forever. At some point, The Man of Steel will deal with the voices inside his head. Stay tuned to Bam Smack Pow to see when that happens.