After introducing the teenage superhero Boy Thunder in an early story arc of Batman/Superman: World's Finest and revealing him to be the eventual antihero Magog from the seminal story Kingdom Come, Mark Waid and Dan Mora are returning to the world of Kingdom Come in the latest World's Finest storyline. Starting in Issue #20, Batman and Superman will explore Earth-22, the alternate universe where Kingdom Come takes place, to learn what happened to Boy Thunder after Superman's estranged former sidekick was whisked back to his native dimension. The superhero duo will find themselves facing their Earth-22 counterparts as the Kingdom Come Superman and Batman deal with what has become of their world.
Source：https://www.cbr.com/batmansuperman-worlds-finest-kingdom-come-mark-waid-interview/
