September 22, 2011 Wizards of the Coast
If, during a player's declare attackers step, a creature is tapped, is affected by a spell or ability that says it can't attack, or hasn't been under that player's control continuously since the turn began (and doesn't have haste), then it doesn't attack. If there's a cost associated with having a creature attack, the player isn't forced to pay that cost, so it doesn't have to attack in that case either.

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