"Hyper-Tension!, Part 3 of 5: Divided by Zero"
While trapped in the alternate world of the alternate Superboy/Clark Kent , they are both attacked by Black Zero and his stormtroopers.
Superboy/Conner awakens in Black Zero's headquarters, where Black Zero tells Superboy his story of how on his world Superman had died and a clone was made just like Superboy's world only on Black Zero's world Superman never returned and the clone grew to adulthold. He wasn't accepted as the new Superman so he changed his name to Black Zero and conquered his world.
And he plans to conquer all the Earths. Superboy mocks Black Zero saying he would never be able to conquer his world, that's when Black Zero opens a chamber which reveals numerous Doomsdays!