I want to echo the stack point:
The stack is where magic is won and lost (in my opinion). I learned so much through the stack display in manabrew. I am still learning. I do find your stack very hard to use. It would be huge if the actual cards showed on the stack and you could expand them to see their order and read what they do.
I do want to congratulate you on such an impressive app. This must have been, and continues to be, a huge effort.
Wind