You can accumulate Duplicate cards and exchange them for reward chests in the Star Shop.

- Each reward chest in Collection has a value expressed in duplicate card stars. As soon as you accumulate enough card stars from duplicates, the chest becomes available for unlocking.
- If you choose to open the reward chest, the required number of stars will be deducted from your balance. At the same time, the duplicate cards themselves are also spent and disappear from your set.
- Duplicates of Gold cards give you 10 stars for unlocking chests.