Abraxas, as the antithesis of Eternity and the abstract embodiment of destruction, sought to destroy not only the main Marvel Comics universe, known as Earth-616, but all parallel realities as well using a weapon of universal destructive power called the Ultimate Nullifier. The location of the Ultimate Nullifier was unknown except to the Human Torch, a member of the super hero team the Fantastic Four. With the intention of attracting the attention of the Fantastic Four, Abraxas killed another universe's Galactus, and sent his skull to Earth-616, also using the skull as a homing beacon. This caused a disturbance in the space-time continuum, allowing people from other universes to come through the gap left by the head, including another Nova (Frankie Raye). When the Fantastic Four sought the counsel of the Watcher, they found that he had forgotten who he was, and then he became comatose. Eternity told Mister Fantastic of the Fantastic Four that this was caused by Abraxas.
After Mister Fantastic gathered a selection of superheroes to fight the minions of Abraxas on the moon (the home of the Watcher), the Silver Surfer was killed by a mist of micro-organisms as he attempted to defend the Watcher from them. The minions seemed to seek the Human Torch, and after investigation it was discovered that he possessed the coordinates of the Ultimate Nullifier. However they were not only within the mind of their Human Torch, but split between the minds of three other Human Torches in alternate universes.
After finding these alternate Human Torches, and passing on the information to the Human Torch of Earth-616, the Fantastic Four found the Ultimate Nullifier. However they were betrayed by the alternate version of Nova, who worked for Abraxas. Abraxas then seemingly destroyed Roma, the protector of Eternity.
After Nova gave Abraxas the Ultimate Nullifier, a battle commenced which the Fantastic Four were losing. However Franklin Richards, Mister Fantastic's son who possessed powers that enabled him to warp reality, and Valeria von Doom pooled their powers and revived Galactus from his star-like remains, though the siblings burned out their powers in the act. The newly reformed Galactus then recalled the Ultimate Nullifier from Abraxas' grasp, revealing to all present that the Ultimate Nullifier was actually a part of his being. Due to interference from Nova the Ultimate Nullifier fell to Mister Fantastic, who realised that the only way to destroy Abraxas was to destroy the whole of reality and recreate the multiverse using the Nullifier. After he does so, those who had died, including the Silver Surfer, were brought back to life, Franklin Richards was left without any power, Valeria is replaced with a new baby inside the womb of the Invisible Woman, and the Watcher was returned to normal.