Fighting Emperor Dragon, Merciless Dragon D-PS01/012 RRR

[Stride]-Stride Step-COST [Choose one or more cards with the sum of their grades being 3 or greater from your hand, and discard them], Stride this card on your (VC) from face down. [AUTO](VC):When your rear-guard [Stand] by a card's ability, COST [Counter Blast (1) & discard two cards from hand], [Stand] this unit, and if it is your main phase, attack your opponent's vanguard with this unit. [AUTO](VC):At the end of the battle this unit attacked, this unit gets drive-1 until end of turn.