Battle Monk of Thunderclaps, Zenshin

[AUTO](RC):At the end of the battle this unit boosted, if you have a grade 3 or greater vanguard with "Triumph Dragon" in its card name, [COST][retire this unit & put a grade 3 or greater card with "Triumph Dragon" in its card name from soul or drop on the bottom of the deck], choose one of your opponent's rear-guards, and retire it. If you did not retire a card, draw a card.