Artifact Creature — Thopter 5/5, 6 (6)

Flying
At the beginning of your upkeep, if you control no Thopters other than Thopter Assembly, return Thopter Assembly to its owner's hand and put five 1/1 colorless Thopter artifact creature tokens with flying onto the battlefield.
Illus. Volkan Baga

6/1/2011: The triggered ability looks for any permanent you control with the creature type Thopter, not just the Thopter tokens previously created by a Thopter Assembly.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern