Vesuvan Duplimancy is a mythic Enchantment card from Dominaria United Promos (PDMU), collector number 73p. Current market price: $7.29 (foil $7.73), TCGplayer market prices via Scryfall.
Whenever you cast a spell that targets only a single artifact or creature you control, create a token that's a copy of that artifact or creature, except it's not legendary.