Power Nullification, or Negation, is the ability to simply nullify the powers and abilities of others, negating their effects. The mechanisms by which this effect is accomplished and their restrictions vary from character to character, but the ability is often limited to a certain type of power, such as supernatural phenomena in general, or magic. In some cases, an ability can only be negated once it's been used or activated, but in others, powers can be nullified before they're even utilized. The effect may be temporary or permanent, and may be restricted by touch, or be something that the user can apply to any ability they see, or within a field that negates any powers within.
Some characters accomplish these effects through applications of other abilities rather than an standalone ability in itself, such as using Power Modification to render powers useless. In addition, there are characters who combine this ability with Power Mimicry to not just seal the abilities of others, but steal them for themselves; this is known as Power Absorption.
It would be a No Limits Fallacy to assume someone with this ability can nullify anything that falls within the phenomena their powers are made to counter. It is to be assumed that any negation power has its limitations based on the strongest thing it has nullified, and a character may be resistant to the ability (at least in one of its forms), preventing it from having its usual effects.
However, certain forms of Power Nullification may prevent the usage of powers through less direct methods, making resistance less useful and the strength of the ability less relevant.
Anti-Magic: Abilities that focus on nullifying magic, potentially even rejecting physical characteristics augmented by magic or making it so that the user cannot be harmed by magic at all. This can negate spells, from simple blasts to more complicated effects, and may be capable of stripping magical items of their enchantments and magical properties.
While useful against magic users, this ability cannot nullify non-magical supernatural abilities, such as those based on chi. A similar ability is known as Counterspelling, which are characters who can counter the spells and magical abilities of others through their own magical knowledge, often requiring some knowledge on the spell to do so.
Immortality / Regeneration Negation: Many characters and weapons have the ability to ignore the immortality and regenerative abilities of their opponents, allowing them to kill characters with wounds they would otherwise survive. As with other powers, this is generally limited by the strongest level of regeneration and the types of immortality that the ability has nullified, and an ability may be limited to just immortality or just regeneration. Killing a character through means they can't survive even with their immortality doesn't count; killing someone who can regenerate from just a soul can just as easily be Soul Manipulation, depending on the context.
Resistance Negation: The ability to bypass the resistances of other characters, such as controlling an opponent with mental defenses superior to one's own level of mental offenses by ignoring the resistance itself. This does not apply to characters who simply overpower the resistance with a power stronger than what their opponent has resisted.