Spellshift is a rare Instant card from Planar Chaos (PLC), collector number 47. Current market price: $0.26 (foil $1.61), TCGplayer market prices via Scryfall.
Counter target instant or sorcery spell. Its controller reveals cards from the top of their library until they reveal an instant or sorcery card. That player may cast that card without paying its mana cost. Then the player shuffles.