Card advantage is very important in this game, even more than in Hearthstone or Magic, since it's also your health. So it's odd watching early enemies play cards which do very little - Attack costs 1 AP, makes me opponent lose a card, and also makes me lose a card (the Attack itself). I'd often rather not play it and let my opponent come to me.
The Necromancer especially - they'd sometimes play their Siphon card at a time when it did literally nothing. And in doing so, leave themselves with 1 card in hand, letting me kill them on my turn.
This strategy worked pretty well until I fought the more control-oriented Blacksmith, and the fight dragged on until both our hands were completely full... of Shields. Some way to break the stalemate would be nice.
In any case, this is a very neat design, good work! The cards slide around the screen very fluidly, and there's an interesting variety of abilities. The animations feel a bit slow sometimes - they were fine when I'm still learning the game, but once I knew what all the cards did I didn't need as much time to read them. As you can see, the rules are deep enough that it makes me ponder the balance and really think about which abilities are most useful. (2AP to draw 3 cards, you say? Gimme gimme!) And good thinking on _forcing_ me to pick a card during the draft - in Slay the Spire, I always found it hard to know when to turn down a card and keep my deck small. Keeping it a choice of "which of these three cards is best?" makes the decision clearer.