Purgatory is a rare Enchantment card from Mirage (MIR), collector number 275. Current market price: $1.57, TCGplayer market prices via Scryfall.
Whenever a nontoken creature is put into your graveyard from the battlefield, exile that card. At the beginning of your upkeep, you may pay {4} and 2 life. If you do, return a card exiled with this enchantment to the battlefield.