Supremacy Black Dragon, Aurageyser Doomed (Secret)

[Stride] (Released when both players' vanguards are grade 3 or greater!)-Stride Step-[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.
[ACT](VC)1/Turn:[Counter Blast (1) & Choose a face down card named Supremacy Black Dragon, Aurageyser Dragon from your G zone, turn it face up, choose three of your rear-guards, and retire them] Reveal two cards from the top of your deck. For each grade 1 or less card revealed with this effect, choose one of your opponent's rear-guards and retire it. Put the cards revealed with this effect into your hand. If the number of face up cards named Supremacy Black Dragon, Aurageyser Dragon in your G zone is three or more, this unit gets [Critical]+1 until end of turn.