I would also suggest the ability to allow/deny a user's hitting rights. Say the guild will only allow high leveled users to attack Chapters 16 and 17. When a user tries to access the lower levels, they will get a message saying something like "You are not allowed to raid this chapter."
But therein presents a few problems:1. What if Chapters 16 and 17 are not open or already completed when the lower chapters are opened only to lower levels?
One of the required dailies is for the player to visit any two chapters in Raid mode, with the rewards being Gaia stone fragments and guild coins. If those chapters are closed or already completed by other players, the user will be left out. I've experienced such situations where a chapter I wanted to participate in was already completed, and if this new concept is set in place, I will be out some guild coins and Gaia stones, not to mention gold.2. What if the game crashes when you enter a raid chapter?
See this: https://www.instagram.com/p/BZolV79nllc/
Basically, that above bug has hindered my gaming experience greatly. I lost out on hundreds of thousands of gold, the chance to claim items, and the possibility of getting the last hit on the Final Boss and bonus. I've actually sent a complaint to customer support about this issue. Unfortunately, because my device is really old, there will be no fixes planned, but maybe you can help future users from the same fate I had.
I would suggest some compensation in the form of gold and guild coins in conjunction with the new rules. An acknowledgement of the daily (automatic completion) may also be in play.