Awesome game, as usual!
I do have some feedback to give, though, regarding the druid.
I find myself not playing him very often, especially after buying and upgrading other cards. The fact that he costs 2 means that I rarely have enough energy to play the druid after more than 2 cards, which makes the payoff of his rune a bit underwhelming.
I think the druid would benefit from having his cost reduced to 1.