|Part I: A Journey into Mystery||Part II: A Contest of Champions||Part III: Strange Adventures||Part IV: The Brave and the Bold|
Krona, an exiled Oan villain from another Universe who has gained the powers of entropy, begins destroying entire universes in his obsession to find out how they are created. The Grandmaster, an alien who is obsessed with games, offers to give Krona the knowledge he seeks but only if he can beat him in a game. The game consists of forcing the Avengers and their heroic counterparts, the Justice League of America (JLA), from that Universe's Earth to battle each other in a race to find twelve items of incredible power that have been hidden around their worlds. With help from Metron of the other Universe, the heroes are tricked into participating. Krona is given the side of the Avengers and Grandmaster is given the side of the JLA.
When Batman and Captain America discover this, Captain America allows the game to end with a victory for the JLA, but Krona refuses to accept this and uses his powers to steal the knowledge directly from the Grandmaster's mind. In turn, the Grandmaster uses the power of the twelve artifacts to merge the two universes, trapping Krona at their center. However, this results in a chaotic world, and Krona begins to cause the universes to collapse, since he now knows that universal creation comes from destruction. The Avengers and the League join forces to stop him, aided by many other members from both teams' pasts (brought together by wild changes in time).
In the end, Krona is turned into a "cosmic egg" from which a universe would be born in a trillion years. The two universes return to normal, with everything that Krona destroyed being recreated as well (this would have consequences for the Anti-Matter Universe, as seen in a further Justice League adventure).
- Red Jar of Calythos
- Silver Wheel of Nyorlath
- Green Bell of Uthool
- Kyle Rayner's Power Battery
- Spear of Destiny
- Eternity Book
- Medusa Mask
- Orb of Ra
- No special notes.
- Superman is the only DC hero to hold both Captain America's Shield and Mjolnir, while both he and Wonder Woman are the only DC characters to have held Mjolnir.
- Hawkeye is the only hero of both universes to be in the both the Avengers and the JLA.