We'd like to cover a few points on Monster Strike's synergy with iOS 10. During our beta tests with iOS 10, we've confirmed that all of the main Monster Strike features (quests, etc.) should function without any problems.
However, it has been confirmed that sometimes there could be problems with inviting friends through social media. There is also a chance that further bugs could be discovered after iOS 10 is released. Whether to update to iOS 10 or not is a choice we'll leave in your hands.
After iOS 10's release, we'll continue to run tests. We'll let you know if we have any new discoveries. Any problems that we find are slated to be fixed in future updates.
Thank you for your patience and Happy Hunting!
*If you have any problems with the iOS 10 update itself, please contact Apple's support team.