Death Star-vader, Quintessence Dragon

-Stride Step-[Choose one or more cards with the sum of their grades being 3 or greater from your hand, and discard them] this card on your from face down. :[ 1 & 1] When this unit is placed on , if you have a heart card with "Infinite" in its card name, you may pay the cost. If you do, choose a rear-guard from your opponent's front row and back row, and lock them. Then, if the number of cards in your damage zone is four or more, the cards locked by this effect cannot be unlocked during your opponent's next end phase.