Spawn of the Spiral Nebula

:Forerunner (When a unit of the same clan rides this unit, you may call this unit to ) (This ability is active if you have one or more face up G units in total on your or G zone):[Put this unit into your soul, choose one of your other rear-guards, and lock it] Choose one of your opponent's rear-guards, and lock it. (The locked card is turned face down, and cannot do anything. It turns face up at end of the owner's turn.)