That's actually how our first version worked but it turned out to be quite awkward to use. For example if you played a 6C with an AS you'd first have to do the maths of (6 + 1) x 2, then you'd have to hit -10, -1, -1, -1, -1 buttons for health, then -5, -1, -1 for attack. With the app now you just tap 4 buttons without having to do the maths.