Gift of Fangs is a common Enchantment — Aura card from Innistrad: Crimson Vow (VOW), collector number 113. Current market price: $0.20 (foil $0.23), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +2/+2 as long as it's a Vampire. Otherwise, it gets -2/-2.