Wow! Thanks for the all feedback. We haven't had a lot of outside feedback so far, so this is very valuable.
We'll have to do something about all the potential farming. It's nice to hear you're getting powerful cards, but we don't want players sitting grinding turn after turn on low level mobs.
I think all the points you raise are very salient. Buffing the campfire seems sensible. Maybe making thinning the deck a bit more expensive/complicated. I'm a fan of creating monster combos in card games, but the combos in Shroom and Gloom don't involve much investment or specialization. Though I think some of that will come naturally with more content (or at least, with more content we'll be able to design more complicated card relationships).
You sound like an expert on card games (moreso than us). I'm going to be borrowing some of your lingo and ways of reasoning about card games!