Scale Up is a uncommon Sorcery card from Modern Horizons (MH1), collector number 179. Current market price: $0.45 (foil $1.34), TCGplayer market prices via Scryfall.
Until end of turn, target creature you control becomes a green Wurm with base power and toughness 6/4. Overload {4}{G}{G} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")