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First strike
At the beginning of each opponent's end step, that player creates a 1/1 red Goblin creature token with "Creatures you control attack each combat if able."
If, during your declare attackers step, a creature you control is tapped or is affected by a spell or ability that says it can't attack, then it doesn't attack, even if you control one of Goblin Spymaster's tokens. If there's a cost associated with having a creature attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either.
