Chapter Text
Quirk: Heads or Tails
In a 1km radius of the user, all quirks, including mutation quirks, are altered to either be less useful or more powerful, however user can't control whether the quirk boosts or depletes someone's quirk. The weaker the quirk, the stronger it gets, and the stronger the quirk, the weaker it gets, with training user could direct who they want to boost or deplete, and possibly be able to decide what classifies as a weak quirk and a strong one. And if trained to the absolute potential, user could boost their own quirk, and then boost it indefinitely until basically nigh-omnipotence.
Examples:
A water manipulation quirk that usually carries 50 tons of water would now only be able to carry 5kg of water, or vice versa.
Someone with a quirk that lets them heal scrapes on knuckles could be able to reattach limbs and heal cancer
And All for One would be able to take quirks after waiting 9001 days while maintaining permanent contact with someone .
This quirk could be great or horrible in combat situations, especially if you could were facing a stronger opponent, the villain would then instantly become substantially weaker, and as a vigilante, or hero, user could boost or downgrade quirks to a level they aren't used to disorienting them, or can't be activated without hurting the user.
If user had a group of weaker heroes, or random civilians with weaker quirks, those people could be able to fight the villain with you.