You missed it because I added it while you were replying. ;)
Overall, I think the balance is fine for the first floor; maybe a little on the easy side. I would keep an eye on the power scaling as you add more floors; my experience is that you tend to either thrash the Minotaur or not make it that far, which means that second floor enemies may need to be much stronger than first floor ones to remain challenging.
Individual cards/artifacts/enemies often vary wildly in power, but that's to be expected in a game of this nature, especially one this young. It's not really a problem IMO, but I can draw your attention to specific examples if you care to start working on balancing them already.