Covert Demonic Dragon, Magatsu Typhoon

:[Legion 21000]"Covert Demonic Dragon, Magatsu Storm"(If your opponent's vanguard is grade 3 or greater, this unit may return four cards from your drop zone into your deck once, search your deck for the specified card, and Legion) :When this unit [Legion], choose up to five of your rear-guards with "Magatsu" in its card name, until end of turn, they get +5000, and "Boost" ([Boost]). :[Choose a card from your hand, and discard it] Choose a unit on your , search your deck for up to one card with the same card name as that unit, call it to , shuffle your deck, and at the end of that turn, return the unit called with this effect to your hand.