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Flying
Whenever a creature attacks, you may pay {3}. When you do, put a +1/+1 counter on that creature.
Anointer of Valor's triggered ability triggers when any creature attacks any player or planeswalker.
If you choose to pay {3}, a second triggered ability triggers. Players may respond to that reflexive triggered ability before the +1/+1 counter is put on the creature.
You can't pay {3} more than once to put more than one +1/+1 counter on the attacking creature.
