I'm using puffin to play and I'm pretty sure others are too, and when playing on puffin you run the risk of losing connection randomly which can cost you arena battles and titan battle turns. So I suggest that arena battles will still go on if the tab closes but you will have to log back in before your turn ends, and for the titan battles make it like in campaign were after you leave when you go back in it saves your progress. Reply, if you think it's a good idea but needs some changes.