Door of Destinies is a rare Artifact card from Magic 2014 (M14), collector number 208. Current market price: $6.92 (foil $15.36), TCGplayer market prices via Scryfall.
As this artifact enters, choose a creature type. Whenever you cast a spell of the chosen type, put a charge counter on this artifact. Creatures you control of the chosen type get +1/+1 for each charge counter on this artifact.