Infinite Crisis Fight For The Multiverse #4

"The Flash, Zatanna and Cyborg find themselves in the Mecha Universe, on an Earth that is not their own, in a futuristic version of Metropolis. Just when things can't get any stranger, a giant, serpent-like version of Doomsday threatens to level the city, and the only one who can stop him is Mecha Superman! Includes a code for a video game content download."