My prediction on how the BAT will pan out goes as follows:
Part 1 – Stars and Stones
]In Part One the stars and planets(Stones) are about to align in the right way for the Outsiders to begin their invasion/bid to destroy our reality and, of course, Harry has no clue. JB has stated that the little girl from “Restoration of Faith”, now grown into another femme fatale, will have a part to play, so I predict that the BAT will start with Faith Astor showing up and manipulating Harry into going on a Quest. During the course of this Quest, Harry will finally get the answers to some of the series most persistent questions. Most probably, what exactly is a Starborn and what exactly was Harry’s mother trying to accomplish by creating one? Of course, Faith will prove to be either an Outsider agent or a dupe and the purpose of her Quest is to trick Harry into being at the wrong place at the wrong time, and doing the One Thing He Should Not Do. The book will end on a cliff-hanger in which Harry looks on at the Outsider army rampaging through the remains of the Outer Gate, or at the monsters escaping from under Demonreach, or at some other disaster he has caused and commenting “Oh $#@&! I just started the Apocalypse. I really shouldn’t have done that.”
Part 2 - Hells Bells
In Part Two the Outsides are rampaging throughout our reality and Harry is desperate to find a way to stop the apocalypse he has started. The answer he comes up with is Harry must go to Hell. Either there is some maguffin in hell, like the Holy Grail from Skin Game, that he thinks will help him defeat the Outsiders, or Harry must do a literal Deal with the Devil in order to bring Hell onside in the battle to save reality from the Outsiders. The book then ends on another cliff-hanger as Harry completes his mission to Hell and returns to the real world only to come face to face with the Big Bad Outsider who has been behind everything in the series revealed at last.
Part 3 – Empty Night
In the finale of the series the Big Bad Outsider behind it all has been revealed in all its horrific glory and it is about to End the World. All that remains is for Harry to gather all his friends and allies and face the Outsiders in one final battle. The battle will be long, fierce and devastating. Each of Harry;s family, friends, and enemies will either rise to the occasion or die trying. The Big Bad Outsider will come close to defeating Harry and company, but Harry will defeat the Outsiders and save the world by pulling off one last ditch Hail Mary play. But the cost of this victory is very steep. Many of Harry’s friends, family, and allies have died to save the world. Mab and Titania have both been killed over the course of the BAT, so the Fairy Courts are in chaos. Most of the Senior Council of the White Council have been wiped out and the White Council of Wizards in in ruins. Even the Vampires and Fomor have been decimated in the battle and have slunk off into the shadows where they belong. In essence, the old order of the supernatural world has been destroyed by the battle and Harry Dresden is left as the Most Powerful Wizard in the World. As the series comes to a close, Harry is now the New Merlin leading the effort to rebuild a new supernatural order. Harry takes a moment from his duties to reflect on how he got here and remarks “You don’t become Merlin by collecting bottle caps.” He then sits down with pen and paper and begins to write out Storm Front and we the reader realize that the series has been Harry Dresden’s account of his rise to power.
Let me know what you think.