We are still in the dark on how and where exactly the LEGO Harry Potter The Monster Book of Monsters (30628) will be distributed but the LEGO database has just updated with the full instructions for this mystery gift with purchase!
There does not appear to be any unique elements and even the Draco Malfoy minifigure is not exclusive so you’ll be able to build this with your own stash or through bricklink. You can download the instructions here.
I’ve also included the parts list below for easier reference.
This highly coveted gift with purchase should be available during the holiday period judging from the release of the instructions and some official product images at this time.