Molten Duplication is a mythic Sorcery card from The Big Score Promos (PBIG), collector number 14p. Current market price: $13.56 (foil $13.59), TCGplayer market prices via Scryfall.
Create a token that's a copy of target artifact or creature you control, except it's an artifact in addition to its other types. It gains haste until end of turn. Sacrifice it at the beginning of the next end step.