As a game rng is really important, its what makes games fun and adds a lot on to the comeback factor. You can see this in games like hearthstone. However, other than crits and turn 1 advantage rng doesn't really play a factor in this game mode. Combo should come hand in hand with your turn 1's mystery, and the ninja pool is the same for both players. And for the main, I would say earth is unviable as of right now, with wind and water at the top. Sharkbomb+experimental nin and poison tai, puts you way ahead of earth main even with elemental leverage.