My idea:

Billie finds the book "Harry Potter VII" at Magic school.
She starts reading it and it sucks her into the story.
Now the girls must go into the book and get Billie out with the help of some
magical trio from within.
Will they come out safely or will they have to vanquish the evil within to get out?
It's basically about the Charmed ones going into the final HP book and basically writing the whole story inside it.
This will be fun and no spoilers about the 7th book.
Though there are possible spoilers from previous books.
xD
Anyone up for it?
I promise I'll let it just go this time xD
Or should I just do a fanfic?