Star-vader, Venom Dancer

:[Legion 20000]"Star-vader, Sword Viper"(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 At the end of the battle that this unit attacked a vanguard, if this unit is [Legion], you may pay the cost. If you do, for each of your opponent's locked cards, choose up to one of your rear-guards, and it. : 1-card with "Star-vader" in its card name] If you have another unit in your middle column, choose one of your opponent's rear-guards in the back row, and lock it. (The locked card is turned face down, and cannot do anything. It turns face up at end of the owner's turn)