Retrofitter Foundry is a rare Artifact card from Secret Lair Countdown (SLC), collector number 18. Current market price: $0.84 (foil $1.34), TCGplayer market prices via Scryfall.
{3}: Untap this artifact. {2}, {T}: Create a 1/1 colorless Servo artifact creature token. {1}, {T}, Sacrifice a Servo: Create a 1/1 colorless Thopter artifact creature token with flying. {T}, Sacrifice a Thopter: Create a 4/4 colorless Construct artifact creature token.