Roar of Resistance is a rare Enchantment card from Phyrexia: All Will Be One Commander (ONC), collector number 15. Current market price: $3.56, TCGplayer market prices via Scryfall.
Creature tokens you control have haste. Whenever one or more creatures attack, you may pay {1}{R}. If you do, creatures attacking your opponents and/or planeswalkers they control get +2/+0 until end of turn.