Sky Guardian Supreme Dragon, Impede Dragon

-Opponent Turn's Guard Step-[Discard a card with [Heal] from hand], and call this card to your from face down. :When this unit is placed on , [turn a from G zone face up], your opponent chooses one of their rear-guards, retires it, and binds it. Then, if the number of your rear-guards is less than your opponent's by two or more, your opponent chooses one of their rear-guards, and retires it.