To accommodate more defensive teams, it would be appreciated if you could add at least 1 more minute to Arena Battles, to avoid "draws" that should have been either victories or losses. You could also add a draw option in the in battle menu and give infinite time. That way, rank would not be affected either way, and players can take their time devising a strategy Bonus protection, health recovery, etc. can add depth to character, however that also means they take longer to kill. For teams relying heavily on multiple tanks or support characters, or two attackers for example, more time would be helpful.