Hi! It would be really useful if the game could notify you when players in your battle/dungeon/group lose connection. It could appear as a message in the chat saying "[Player name] lost connection!" or something like that. That way, you're not wondering what happened to that one person in battle, or other players don't think I logged out on them if I actually lost connection.
...Also, when players lose connection in battle, often times their character will linger and take up the whole 30 seconds of a card selection. It would be nice if the game could make them automatically pass until they rejoin or their character disappears.