MTG Salvation

6/15/2010 Annihilator abilities trigger and resolve during the declare attackers step. The defending player chooses and sacrifices the required number of permanents before they declare blockers. Any creatures sacrificed this way won’t be able to block.

6/15/2010 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.

6/15/2010 If, during your declare attackers step, Ulamog’s Crusher is tapped, is affected by a spell or ability that says it can’t attack, or is affected by “summoning sickness,” then it doesn’t attack. If there’s a cost associated with having Ulamog’s Crusher attack, you aren’t forced to pay that cost, so it doesn’t have to attack in that case either.