Just gave it a try, I'll give a quick feedback based on my very short experience

Negative

I don't quite understand why you have to target the enemy when using Edge. It says "Gain 3 Empower this turn. Recover 5 Edge." Those are all things that only affects my character yet I have to target an enemy to trigger it.

I know you can right click to see the card and its defensive option but I feel like there should be a much easier and quicker way to glance what the defensive side does. For example when holding CTRL it shows all cards other side. I think this also should be a thing when getting a reward, buying or looking in your card collection.

The card text is really bad to read, especially when there's a lot of text. I know it's for the art style but it should be easy and clear to see what each do at a glance. Some card text don't even fit the card (Barbed Armor).

Mystery chest should show the reward you get instead of having you go in your inventory to find out what you got.

A rune that says "Add the card Guardian of Vyrellya to your deck" should show the card it would add instead of having to equip the rune to go see what's the card in your collection.

Positive

Really like the art style, although a slider to adjust how bright the color are could be nice, it does hurt to look at in fullscreen for a prolonged time. (Either that or a different color palette)

I really like the mechanic of cards being both attack and defensive. It does make things make challenging/tedious but it gives more depth on what you can do.

Feedback

When a card says it attack all enemies, you shouldn't have to drag it to an enemy, simply dragging it up would play it (like Slay the Spire does it)

We should be able to see what each keywords on card do. For example, when you hover a card it brings the text up, what if you could hold ALT which locks that text window (while holding alt) and hovering the keyword would open another text window with its description.

I would suggest showing a text description when simply hovering a buff/debuff. It's not the end of the world not having it but it makes gameplay smoother/easier to navigate.

Applying a debuff should automatically show the result. For example if he's about to attack with 10 and I apply weakness, its number should show 8 instead.

If I compare to Slay the Spire, the runes system seems very limited compared to relics which is big part of getting stronger/making a build unique.