Stab Wound is a common Enchantment — Aura card from Return to Ravnica (RTR), collector number 78. Current market price: $0.19 (foil $0.61), 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.