Voidmage Prodigy is a rare Creature — Human Wizard card from Onslaught (ONS), collector number 120. Current market price: $8.10 (foil $100.50), TCGplayer market prices via Scryfall.
{U}{U}, Sacrifice a Wizard: Counter target spell. Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)