Could you look into starting a trading store.
Make it players have to be a certain player level before they can access it. E.g. 50 or 100 or so forth. Or finish the world map stages.
Let us trade characters in return for items, weapons, trainers and coins. People will still need to buy these resources or purchase membership to get ahold of what they need for trades. It would allow people to get rid of their duplicate characters. Would give others opportunities to get ahold of characters they never would have before.
Right now people could have bought 4* for the roadmap event. Most people dont retain them.
Even if you made people could only trade 5* (including ascendables) and below that way S Class Characters would have to go through your collections.
It would make the game lots more fun because you could get the collections in the museum completed.
It would also draw alot more players to stay on the game I think.
See what others think. It’d be a major selling point for the game.
Would help with your ascendance quests too. Not many people have 5 ascensions worth of characters lying around.