Balefire

From A Wheel of Time Wiki

Balefire is a weapon of the One Power usable by both male and female Aes Sedai. Its widespread use during the War of Power began to cause the Pattern to unravel, and it was subsequently banned from use by all wielders of the One Power.

When a target is struck with balefire, its thread in the pattern is destroyed, in an amount proportional to the power of the balefire strike. This translates to the target's existence being completely erased chronologically. For example, should an Aes Sedai use balefire on an attacking bandit, the bandit's action of attacking the Aes Sedai and anything leading up to the action of the attack would be erased, this would be determined to the power of the balefire attack.

Balefire is used several times by Rand al'Thor (who uses it against a Darkhound on instinct) and Nynaeve al'Meara before Moiraine Damodred warns them of its dangers.

Balefire can even bring people back from the dead; both Aviendha and Mat were brought back to life, or saved from death when Rahvin was balefired with enough force to undo his attack that caused their deaths. Mat was saved when the Darkhounds attacking him were burned away before injuring him.

An interesting side effect of using balefire is that anyone that is affected by the "reversal" of time will still remember all the events that were undone as if they had actually happened even if the effects themselves no longer exist.