Harbin, Vanguard Aviator is a rare Legendary Creature — Human Soldier card from The Brothers' War Promos (PBRO), collector number 212p. Current market price: $0.56 (foil $0.59), TCGplayer market prices via Scryfall.
Flying Whenever you attack with five or more Soldiers, creatures you control get +1/+1 and gain flying until end of turn.