Taj-Nar Swordsmith is a uncommon Creature — Cat Soldier card from Mirrodin (MRD), collector number 27. Current market price: $0.25 (foil $0.49), TCGplayer market prices via Scryfall.
When this creature enters, you may pay {X}. If you do, search your library for an Equipment card with mana value X or less, put that card onto the battlefield, then shuffle.