Dang, for a moment there I thought this post wasn't gonna have a deadlock waiting for me. Just one quick question, do you remember if your enemy discard the card as a part of its cost or did it lock before that? Also did he only had the 0 cost card in hand when he played it, or did he also had that 2 cost blue card? (Don't worry if you don't remember any of these details, the screenshot is plenty either way).
I also appreciate the balance feedback, you might be right about exhume, I'll probably rebalance that! Although keep in mind that the game goes up in difficulty up to the 50th successful run you complete, so while you are overpowered now, you are eventually gonna need to be very overpowered.
This said, it might be boring if it's too trivial to win on the early runs. Balancing is very undertested at the moment, so your comments are much appreciated and will be taken into account!