Stab Wound is a common Enchantment — Aura card from Duel Decks: Jace vs. Vraska (DDM), collector number 72. Current market price: $0.28, TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets -2/-2. At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.