Perplex is a common Instant card from Ravnica: City of Guilds (RAV), collector number 217. Current market price: $1.63 (foil $16.31), TCGplayer market prices via Scryfall.
Counter target spell unless its controller discards their hand. Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)