Don't bump the deck to 35 cards, that will make all your draws a lot worse. Also, this deck won't fare well unupgraded due to how expensive the cards are. Some cards are not essential to be upgraded (like the lava golem and the graboids, or the forest spirit), others are just too expensive if not upgraded.
Here's a bare minimum that you need, but your winrate will obviously be lower because you have much lower damage. It is not really recommended. Towers can be unupgraded too, but then you are better off using another deck. Focus as well, I just don't have an unupgraded version of it.
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As for the RNG-rage, it happens to each and every one of us. We've just learnt to live with it, more or less. But are you sure it's a good idea to put in one-time spells into a deck like this? The power of these rainbow decks come from all the reusable effects.
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The SN/nova split is surprisingly effective, and with 3 SoFos and the Rage Elixir/Eagle's Eye(snipe once and you have another PC)/GPull you have a lot of PC.
Seems interesting, I will have to try these variants some day when I overcome my disgust for the arena.