Soooo, I don't know how many other players have this problem, but I'm sure it's more than a few. You get to the upper tiers of Snow wars and you're running low on the boosts you use the most. However, you are sitting on a stack of 50-100+ fort boosts that you are NEVER going to need all of. Therefore, there should be a way to trade or exchange boosts within the game. Say trade 3-5 of boost X for 1 of boost Y. This way, players can trade the boosts they don't use for ones they actually need. The forts are the most annoying, I get that you use the fort in EVERY game, but at the same time you only use ONE. In my personal case, I hate towers too. So I got tons of tower cards which I don't want to use because I hate that unit. And those cards sit there and basically represent a huge loss of money and resources. It would make the game feel a little more balanced and fair, especially considering how hard the last tier is and how much money it costs to buy boosters and cards off of other players.

Also, there should be a rank upgrade option. It is impossible to win a tier 6 game without a healthy number of purple and gold units. That being said, winning tier 6 games all comes down to "were you lucky enough to find enough purple and gold cards to make it through" and that's not cool. There should be a way to upgrade blue cards (again, about a 5-1 ratio) so the blue cards that are now as useless as extra fort cards can be put to use.

Edit: By the time I finally gave up of actually getting the tier 6 prize (due to being frustrated enough I literally had an emotional breakdown and deciding that to take this seriously any longer was bad for my health) and just made one all-out push to see how far I got, I made it to a 3100 high score by the time I ran out of purple and gold boosts of the units I used. I even started using towers to "distract" enemy cannons and save my own cannon cards. I also was sitting on stacks of blue fort and tower cards that were over 120 cards EACH.

Conclusion: If these two small (and reasonable) changes were made, I, and probably more players too, would have been able to get the prize. I understand It's supposed to be hard, but when the final level is dependent solely on if you were lucky enough to get enough high-end boosts to make it through, there should be a way to trade/upgrade them.