Bi-attack Dragon

/:When this unit attacks a vanguard while boosted, 1, choose a column, and retire all of your opponent's rear-guards in that column. (Hand):At the beginning of your ride phase, if your vanguard is grade 1 or less, [discard this card], look at the top five cards of your deck, choose up to one grade 2 or less card from among them, reveal it and put it into hand, and shuffle the deck.