Ranking in Duel determines how strong your lineups are. The more opponents you defeat, the more Duel Points you receive.
After each Weekly Rankings reset every sunday at 20:00, you will be rewarded based on the rank you reach before the reset. You can check the rewards in the Ranking interface in the Duel menu.
1. Tap on in your Hideout or Mission Map.
2. Choose the interface for Duel in the Mode Selection.
3. Tap on the "Ranking" Button.
4. On the Selection Tab below, tap on the "Ranking Rewards"
Take note that if you have been defeated when you challenge or when you have been challenged by another player, your rank decreases -- Choose your opponent wisely!
You can check out the current ranking of all the players including yours, by tapping "Ranking" icon in the Duel interface.