Toolcraft Exemplar is a rare Creature — Dwarf Artificer card from Kaladesh (KLD), collector number 32. Current market price: $0.25 (foil $0.40), TCGplayer market prices via Scryfall.
At the beginning of combat on your turn, if you control an artifact, this creature gets +2/+1 until end of turn. If you control three or more artifacts, it also gains first strike until end of turn.