Shell of the Last Kappa is a rare Legendary Artifact card from Champions of Kamigawa (CHK), collector number 269. Current market price: $0.70 (foil $12.50), TCGplayer market prices via Scryfall.
{3}, {T}: Exile target instant or sorcery spell that targets you. (The spell has no effect.) {3}, {T}, Sacrifice Shell of the Last Kappa: You may cast a spell from among cards exiled with Shell of the Last Kappa without paying its mana cost.