Tomorrow (August 26) is the official release of Book 6: Escape From Lucien! Some people (like me) have already managed to read or get ahold of the book through advance reader copies and special events.
If you haven't already seen my review of the book and don't want any spoilers, I will say that at least four new characters are introduced, including a female elf mayor named Riva and a robot named General Pil. As Kazu stated, the book also reaches some closure on Max's story arc.
Please note that the What do you want to see in Book 6? discussion thread will be closed soon after the release date. Good luck, and hope you all enjoy the long-awaited new book!