Thopter Assembly is a rare Artifact Creature — Thopter card from Duel Decks: Elves vs. Inventors (DDU), collector number 63. Current market price: $0.38, 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.