Vexing Sphinx is a rare Creature — Sphinx card from Dominaria Remastered (DMR), collector number 297. Current market price: $0.21 (foil $0.33), TCGplayer market prices via Scryfall.
Flying Cumulative upkeep—Discard a card. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) When this creature dies, draw a card for each age counter on it.