Sai, Master Thopterist is a rare Legendary Creature — Human Artificer card from The Brothers' War Commander (BRC), collector number 93. Current market price: $0.69, TCGplayer market prices via Scryfall.
Whenever you cast an artifact spell, create a 1/1 colorless Thopter artifact creature token with flying. {1}{U}, Sacrifice two artifacts: Draw a card.