Circle of Confinement is a uncommon Enchantment card from Innistrad: Crimson Vow (VOW), collector number 7. Current market price: $0.16 (foil $0.20), TCGplayer market prices via Scryfall.
When this enchantment enters, exile target creature an opponent controls with mana value 3 or less until this enchantment leaves the battlefield. Whenever an opponent casts a Vampire spell with the same name as a card exiled with this enchantment, you gain 2 life.