Sky Guardian Supreme Dragon, Impede Dragon D-PV01/087 C

[G guardian] (Usable when both fighters' vanguards are grade 3 or greater, and the number of face up G guardians in your G zone is three or less)-Opponent Turn's Guard Step-[Choose a card with "Heal" from your hand, and discard it] Call this card to your (GC) from face down. [AUTO] Generation Break 1:[Choose a face down G guardian from your G zone, and turn it face up] When this unit is placed on (GC), you may pay the cost. If you do, your opponent chooses one of his or her rear-guards, retires it, binds it face up, and if the number of your rear-guards is less than your opponent's rear-guards by two or more, your opponent chooses one of his or her rear-guards, and retires it.