Mox Tantalite is a mythic Artifact card from Modern Horizons (MH1), collector number 226. Current market price: $10.74 (foil $24.63), TCGplayer market prices via Scryfall.
Suspend 3—{0} (Rather than cast this card from your hand, pay {0} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.) {T}: Add one mana of any color.