Hi! Thank you so much for trying out the game, I'm really glad you're enjoying it!
As for your suggestions, I'll definitely keep them in mind! I wanted rare cards to be harder to obtain so they would feel more special and rewarding. But maybe I made them a bit too difficult to get. It's something I could balance a little better or improve by adding some of the upgrades you mentioned.
Thanks again for taking the time to share such detailed feedback! I'll be looking into your suggestions and working on ways to improve the game!