And, maybe I'm just a little slow, but there seems to be no way to undo a card selection just before starting a battle. Sometimes I accidentally click on the wrong card and end up having to play it unnecessarily.
I think that it is intended that you cannot undo a card selection. The reason for it is that your opponent(s) can see the card once you have played it. So, being able to undo a card selection would lead to everyone trying to overtrump the cards of the other player(s) by incessantly deselecting and selecting cards.
