Silver Surfer, Air-Walker, Firelord, Nova and Morg (If needed, the Fallen One can be summoned)
Superman, Wonder Woman, Green Lantern, The Flash, The Batman, Aquaman, Martian Manhunter (Captain Marvel is standing by if needed, watchtower is fully armed and ready, the JLA may use anything from the armory and trophy room)
The Heralds are en route to Earth where they plan to destroy its defenses and offer it to Galactus so that he may devour the DC universe. In exchange, Galactus will never feed in the Marvel U again. The Heralds are bloodlusted.
Back on Earth, Watchtower detects the approaching forces and assess them to be hostile. Batman gathers the JLA and they prepare for the invaders. They have one week to prepare.
The battle is over when the defenders or the attackers are KO or KIA.