Sai, Master Thopterist is a rare Legendary Creature — Human Artificer card from Core Set 2019 Promos (PM19), collector number 69p. Current market price: $1.56 (foil $7.20), 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.