Steamflogger Boss is a rare Creature — Goblin Rigger card from Unstable (UST), collector number 93. Current market price: $0.39 (foil $0.37), TCGplayer market prices via Scryfall.
Other Riggers you control get +1/+0 and have haste. If a Rigger you control would assemble a Contraption, it assembles two Contraptions instead.