The Ultimate Nullifier has the ability and power to completely and utterly eliminate any target the wielder chooses but to cause this it has to go through violation of the law of conservation of mass itself, the weapon is used based on the wielder's mind. In this case a being like Galactus who is Nigh-Omniscient can use the Ultimate Nullifier to destroy entire time-lines from beginning to end and instantly nullify it while also paradoxically can recreate something it destroyed and this can be from a universe to a multiverse while creating a new time-line in a alternate universe causing a new existing event.