Slumbering Tora is a rare Artifact card from Betrayers of Kamigawa (BOK), collector number 161. Current market price: $0.27 (foil $0.75), TCGplayer market prices via Scryfall.
{2}, Discard a Spirit or Arcane card: This artifact becomes an X/X Cat artifact creature until end of turn, where X is the discarded card's mana value.