'Annihilator' was introduced in the Zendikar block in Rise of the Eldrazi. It is tied to the 'Eldrazi' creatures of the set, monstrous beings dedicated to destroying everything around them.

702.83. Annihilator

  • 702.83a Annihilator is a triggered ability that appears on some creatures. "Annihilator N" means "Whenever this creature attacks, defending player sacrifices N permanents."
  • 702.83b If a creature has multiple instances of annihilator, each triggers separately.

Rules Translation

  • 702.83a Defending player sacrifices N permanents in response to the creature attacking.
  • 702.83b It does happen multiple times if somehow it gets more than one instance of Annihilator.

Notes from the Rise of the Eldrazi FAQ

  • The defending player is the player that the creature with annihilator is attacking, or the controller of the planeswalker that the creature with annihilator is attacking.
  • Annihilator abilities trigger and resolve during the declare attackers step. The defending player chooses and sacrifices the required number of permanents before he or she declares blockers. Any creatures sacrificed this way won't be able to block.
  • If a creature with annihilator is attacking a planeswalker, and the defending player chooses to sacrifice that planeswalker, the attacking creature continues to attack. It may be blocked. If it isn't blocked, it simply won't deal combat damage to anything.
  • In a Two-Headed Giant game, the controller of an attacking creature with annihilator chooses which of the defending players is affected by the ability. Only that player sacrifices permanents. The choice is made as the ability resolves; once a player is chosen, it's too late for anyone to respond.

Possible misspellings: Anihilator, Annihilitor, Anihilitor, Annihalator, Anihalator