Justice League of America #29

The Crime Syndicate is so bored of life on their Earth as supreme villains, designated as Earth-3, that they come to the JLA's Earth for a new challenge after Ultraman accidentally discovers it when exposed to Green Kryptonite (which gives him a new power with every exposure to it). Just as it looks like the JLA has the upper hand, the Crime Syndicate teleports them to Earth-3, where they have the advantage. To secure a level battlefield the Crime Syndicate plans to go to the Earth-2 and eliminate the JSA.