Door of Destinies is a rare Artifact card from Tales of Middle-earth Commander (LTC), collector number 277. Current market price: $4.70, 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.