Frontline Medic is a rare Creature — Human Cleric card from Gatecrash (GTC), collector number 12. Current market price: $0.21 (foil $2.38), TCGplayer market prices via Scryfall.
Battalion — Whenever this creature and at least two other creatures attack, creatures you control gain indestructible until end of turn. Sacrifice this creature: Counter target spell with {X} in its mana cost unless its controller pays {3}.