Thopter Assembly is a rare Artifact Creature — Thopter card from Mirrodin Besieged (MBS), collector number 140. Current market price: $0.36 (foil $2.77), TCGplayer market prices via Scryfall.
Flying At the beginning of your upkeep, if you control no Thopters other than this creature, return this creature to its owner's hand and create five 1/1 colorless Thopter artifact creature tokens with flying.