Once you have done everything you can for the day (without buying more crystals) there is simply nothing to do. The regen rate is simply way too slow. I think it would be cool to have a practice arena where you get no rewards. Basically some place to test new combinations of teams and such. It sucks only being able to play for a short time a day. I know EA wants us to buy crystals, and I do from time to time....but I am not going to buy them every day.