Cartouche of Strength is a common Enchantment — Aura Cartouche card from The List (PLST), collector number AKH-158. Current market price: $0.17, TCGplayer market prices via Scryfall.
Enchant creature you control When this Aura enters, you may have enchanted creature fight target creature an opponent controls. (Each deals damage equal to its power to the other.) Enchanted creature gets +1/+1 and has trample.