Arcane Subtraction is a common Instant card from Strixhaven: School of Mages (STX), collector number 36. Current market price: $0.07 (foil $0.22), TCGplayer market prices via Scryfall.
Target creature gets -4/-0 until end of turn. Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)