I liked the use of cards to select what towers/upgrades to place, but was a bit confused on which enemy types where which, as well as had a few starts where I had no towers to choose from and was only given upgrades.
I added the redraw mechanic which should decrease the chance of a bad starting hand by a lot. And I agree with lack of ability to differentiate enemies. It took me about 5 minutes to make each sprite and due to lack of time I couldn't add any other indication. Thanks for feedback.