An Ultimate Nullifier is a unique Weapon of Mass Destruction (or in some cases, a Person of Mass Destruction) with the power to completely destroy a target: no saving throw, no take-backs, the target is just gone. At the very least, it completely disintegrates the victim. In extreme cases, it destroys the victims soul as well as body. In really extreme cases, it can erase them from time completely, such that they never existed in the first place. I'm not sure if there is a version of this trope under a different name already. If not, it could be too rare to trope, though it does come up fairly often IME. Mainly a Comic Books trope, though it shows up in Science Fiction and Fantasy as well. Examples: Marvel Comics: the proposed Trope Namer is, of course, Galactus' Ultimate Nullifier, a weapon which in the wrong hands could threaten all existence. Whateley Universe: Tennyo is bound to an ancient weapon designed to destroy Great Old Ones. Her 'death strike' can completed destroy virtually any target she chooses, both physically and spiritually, to the point that even the sub-atomic particles they are composed of disintegrate over a short period of time.
Hello, Unknown Troper. You'll need to get known to lend a hand here.