Hello!

About your inquiry about power decrease, there's a lot of things that might happen in your character. The most probable cause of the power drop are the Group's Summon or your Moon and Sun Scroll Power, like what people above me said. Aside from that is the possibility of your team setup, changing ninjas and its equipment or positions might also affect your power so be sure to check all possibilities to track where the decrease came from.

And about the Moon Scroll Limit, there is the default limit for each player as far as I know, if you haven't reached the maximum limit of your Moon Scroll for this week, half of the unused limit will be added to your next week's limit. But if you reached the maximum limit of it, nothing will be added to your next week's.

Hope my response shed some light on your problems. Thank you.