Free Duel
This mode lets you battle against a player of your choice. The basic rules are the same as Favor Battles, but you won't gain any Favor. You'll also need to share a password with your friends in order to match up with one another.
Setting Custom Rules
In Free and Practice Duels, you can customize your battle by adjusting the time limit, choosing the map, and more. Use the settings of your choice when you want to play with your friends, or if you just want to get a little practice in.
If You Can't Get Matched Up
If you're having trouble matching up for battle, be sure to check that you and your friend are both using the same password, and try changing the custom rules setting to Opponent Chooses. If both players are set to Custom Rules, it may be difficult to be matched up.
Practice Duel
This mode allows you to practice Summoner Duels against AI opponents instead of being matched up against other players. You can use Practice Duels to test your strategies and see how they pan out.