Star-vader, Dark Zodiac

:[Legion 20000]"Star-vader, Astro-reaper"(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) : 1 When this unit [Legion], you may pay the cost. If you do, all of your opponent's locked cards cannot be unlocked during his or her next end phase. :[Choose a card with the same card name as a unit on your from your hand, and discard it] Choose a rear-guard in your opponent's front row and back row, and lock them. This ability cannot be used for the rest of that turn. (The locked card is turned face down, and cannot do anything. It turns face up at end of the owner's turn.)