Darkness that Lights Up Demise, Lacus Carina

(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] Heal" from your hand, and discard it] Call this card to your from face down. :[ 1 & Choose a face down G guardian from your G zone, and turn it face up] When this unit is placed on , you may pay the cost. If you do, choose up to three of your rear-guards, lock them, and your opponent locks one of his or her units in the back row for each card that was locked.