Tawnos's Tinkering is a common Instant card from The Brothers' War (BRO), collector number 191. Current market price: $0.16 (foil $0.20), TCGplayer market prices via Scryfall.
Put two +1/+1 counters on target artifact, creature, or land you control. Untap that permanent. If it isn't a creature, it becomes a 0/0 creature in addition to its other types.