Not related to actual gameplay.

1) The zoom via mousewheel mouse only has 2 settings and they hardly change the display not sure if the engine can support it but it'd be nice to get closer to the action (pan down and up more)
Maybe a setting to temporarily zoom close during spells/combat would be nice also.

3) more deck slots please!, theres a LOT of pantheons now and many many cards, so you should let people experiment and have as many decks with different pantheons that they want.
I'm sure the deck storage is negligible in size.
Dont follow some earlier digital card games that ignored this most basic and necessary addition.
Unless you're going to put an export string/import string so they can keep the deck info on their own computer in text form which would be fine also.