Mishra, Excavation Prodigy is a uncommon Legendary Creature — Human Artificer card from The Brothers' War (BRO), collector number 140. Current market price: $0.12 (foil $0.33), TCGplayer market prices via Scryfall.
Haste {1}, {T}, Discard a card: Draw a card. Whenever you discard one or more artifact cards, add {R}{R}. This ability triggers only once each turn.