Blue Storm Dragon, Maelstrom

:[Discard a card from hand], choose a unit card with only 《Aqua Force》 for its clan or a ＜Tear Dragon＞ from your soul, call it to , it gets ":When this unit attacks, if your opponent's vanguard is grade 3 or greater, and it is the first battle of this turn, 1, and this unit." until end of turn, and at the end of that turn, put it into your soul. :When this unit attacks a vanguard, if it is the fourth battle of this turn or more, draw a card, choose one of your opponent's rear-guards, and retire it.