I would like to see more opportunities to use massive resources. For instance, my electrum is in the 5 figures and has been for some time. I have plenty of copies of the cards in the bazaar and the vast majority of my cards are upgraded. I would like to buy nymphs but realize this has already been addressed. What about allowing players to auction their cards? Once a month, everyone is allowed to submit one card for auction and players bid by blindly on each submission. In this way, people could get to the auction on their time yet cards would not change hands too rapidly. This would also help beginners who want quanta more than that one rare they happened on early in. Hell I'm not even sure how to get shards aside from starting from the beginning...
Shard of Prosperity - All pillars and towers produce double quanta. Upgraded - All your pillars and towers produce double quanta.
I would also like to leverage massive resources in game - i.e. with a rainbow deck, take 50 quanta from all 12 types and throw a massive fireball for 500 damage at your opponent. Take 20 from each of the 12 types and your opponents creatures attack him alongside yours for one turn. Achieve 75 quanta in each of the 12 types with full health and instantly win.
Also towards that end, are cards ever going to get upgraded a second time? Will we ever have an arena where you can bring 200 card decks and play with 1000 hp? I know this can get ridiculous and unbalanced, but some of these matches get over with too quickly. With 1000 hp, a slow deck has time to get up to speed...