Giltspire Avenger is a rare Creature — Human Soldier card from Conflux (CON), collector number 108. Current market price: $0.75 (foil $0.92), TCGplayer market prices via Scryfall.
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) {T}: Destroy target creature that dealt damage to you this turn.