I don't have a name for this book yet...

a long long time ago, the Sky Shadows, dark mist-like beings, used to rule all the many universes and dimensions. they kept balance in peace in the worlds. until, everything started to come apart. darkness was spreading amongst the worlds, and universes were breaking. not even the Sky Shadows, the greatest beings alive could find out what it was. a young universe balancer who went by the nickname "Moon" realized that things were off. and she went to the sky shadows in search of guidance, but found none... after a long time of thinking she knew what she had to do.
~~~~~~present day~~~~~
Cassie is a Mewla girl who lives on her own in a treehouse. one day, as she is looking through some of her old books at the back of her treehouse, she finds an ancient book; a diary from her great great great great great great great great great great great great great grandmother, Moon. as well as finding out what Moon did to save the universes, Cassie accidentally finds hidden things that she was never meant to know... secrets that had been long buried for thousands of years... and the knowledge that a new darkness is coming. and she is the only one who can stop it
(this story is still a very early draft. this description will almost definitely change when I get further along in writing the story)