Security Upgrader

:If you have a grade 3 or greater vanguard with "Seraph" in its card name, and you did not ride this turn, [retire this unit], search your deck, hand, or drop for up to one grade 4 unit card with "Seraph" in its card name, ride it as , and if you searched the deck, shuffle the deck. If you rode the card, your opponent chooses a card from their drop, imprisons it in your prison, and the cost of the original ability of that ridden unit decreases by 1 until end of turn.