Sphinx's Tutelage is a mythic Enchantment card from Special Guests (SPG), collector number 75. Current market price: $5.38 (foil $9.41), TCGplayer market prices via Scryfall.
Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process. {5}{U}: Draw a card, then discard a card.