I really like cubics but they have a hard time making plays since they have a huge contradiction in design: You want to run lots of Cubics so that you can summon Nova, but only Duja and Karma do anything to help you get him out (or really do anything but sit in your hand) so you don't want to run a lot of dead cards
Dusknoir is certainly going to be a card to watch out for, and will likely change the way some players approach the game
Right now, I would say three, since that's the casting cost of many counterspells, but the number that matters is the one for this set
The deck is a White, Blue, and Green (or, Bant) deck that revolves around creatures that enter with +1/+1 counters, that synergise with Tidus, Yuna's Guardian's abilities
Yugi puts on the Puzzle and continues the Duel, as the effect of "Crimson Nova Trinity" inflicts the damage that Yami Diva took to Yugi, but Yugi discards his "Clear Kuriboh" to reduce the damage he takes to zero