Poking at this after the update. Some thoughts:
After unlocking the deck selection tab, I clicked through, started a new run, and was immediately really confused about not being able to pick a deck. I figured out that I need to pick the deck while between runs, but I think it'd be smoother if the game let you pick what deck you want at the start of each run.
The Mage nerf makes the game feel way worse to me - in previous updates, I found myself ignoring the Mage until I reduced its cost to 1 because paying 2 to draw a card feels overpriced. Comparing it to the other 2-cost cards in the starting deck, you've got the Elks (which offer two strong runes for different builds), the Mirror (doubles the next card which opens up some cheeky plays), and the Dryad (tons of snowball potential).
Part of my problem here is that in most trials you're only going to see a card 2-3 times - if the Mage feels awkward to play for one turn, that awkwardness is going to show up over and over again. Contrast that with the (upgraded) Wanderer, where it feels solid every single time you play it. The Mage just needs something, I'm not sure what.
EDIT: I've been messing around with the Wild deck - I really like how the Nekomata and Stalker encourage you to sequence your cards differently, and the Shaman's Spellbind rune is a lot of chaotic fun.
Playing around a bit with the Shaman makes me think that Mana Drop would be a really sweet transient rune.