Isildur's Fateful Strike is a rare Legendary Instant card from Tales of Middle-earth Promos (PLTR), collector number 91s. Current market price: — (foil $1.89), TCGplayer market prices via Scryfall.
(You may cast a legendary instant only if you control a legendary creature or planeswalker.) Destroy target creature. If its controller has more than four cards in hand, they exile cards from their hand equal to the difference.