Darkseid and Magneto have teamed up to conquer Marvel's Earth, while the JLA, the Avengers, the X-Men and the Young Heroes join forces to oppose them. As the heroes make plans to attack Asteroid M where Magneto, Darkseid and their respective minions are based, Access arrives with Redwing (an Amalam of Robin and the Angel). He explains how his abilities allow him to combine heroes to create "Amalgams".
Meanwhile, aboard Asteroid M, as bickering between Darkseid's forces and Magneto's Brotherhood grows into isolated scuffles, the two despots summon Virmin Vundabar and the Toad. Darkseid's cloaked ally lays his hands on the two lackeys with electrifying results. At this point, Magneto and Darkseid observe the Justice League Satellite approach them. The Satellite docks, and the Amalgams calling themselves the X-League burst in: Redwing, Captain America, Jr. (Captain America and Captain Marvel, Jr.), Green Goliath (Green Lantern and Giant-Man), Wonder Wasp (the Wasp and Wonder Girl), Thor-El (Superman and Thor), Jean Black (Marvel Girl and Black Canary) and Quick Freeze (Impulse and Quicksilver).
They are soon met by the Brotherhood of Evil Gods: Sabrebak (Sabretooth and Kalibak), Virmin Vundavort (Vundabar and the Toad), Kantique (Kanto and Mystique), Silverlance (Quicksilver and Devilance), Disastermind (Desaad and Mastermind), Red Lash (Scarlet Witch and Lashina) and Blobba (the Blob and Stompa).
While that battle rages in orbit, the heroes on Earth, overseen by Professor X, fight against the Female Furies and the Deep Six.
Aboard the Asteroid, as Access watches the battle go against the X-League, Darkseid and his hooded ally find him. Access tries to escape through a portal, but it is quickly closed by the ally who reveals himself to by a future self of Access who has joined Darkseid. They commence to fight and their struggle carries them through one amalgamated universe after another. Weakened, the present Access collapses, then realizes he can amalgamate with his future self. He does so and rejects Darkseid's offer to join him.
Darkseid then recalls Mantis and Juggernaut whom he'd assigned to abduct Access' girlfriend Ming. They begin to fight and when Darkseid strikes Juggernaut while hurling an epithet about mutants, Magneto attacks him. Darkseid grabs Magneto by the throat, while Access begins to separate the evil Amalgams. The Brotherhood confronts Darkseid, demanding he release their leader. He does so, dispatching the mutants to Earth.
Darkseid accedes to a draw, and removes his forces, returning to Apokalips. With the heroes victorious, Access returns them to their proper universes. He then seeks out Ming in the present and explains to her that he now belongs to both dimensions, and although he must now leave, he promises he'll be back.