Brandon Sanderson
Siri Is Taken to the God King, Then Discovers Who Is Really Behind the Attacks
I'm hoping that by this point, readers will be very confused about the nature of this third force that is attacking. I hope it's the good kind of confusion, though.
Let me explain. When I write, I sometimes want to inspire confusion. It helps keep the mysteries of the book shadowed and vague. It helps the reader connect with the characters, who—presumably—are also confused. But there's a danger here in being too confusing. If the readers think that they've missed something, or if they can't follow what is going on at all, then they will just put down the book.
The trick is to make certain to telegraph that the characters are confused as well, as I mentioned above. If the reader knows that they are supposed to be searching for answers, then it will be all right. (As long as it doesn't get prolonged artificially.) If, instead, they get the impression that the author has simply made a mistake and isn't explaining things clearly, they'll react very differently.
Anyway, I hope that you have the first reaction and not the second. The twist of who is really behind everything should come as a shock, but I hope that it's also well foreshadowed. The big clincher is the question that, perhaps, you've been asking this entire book. If the war is going to be so bad for everyone involved, then who could possibly be pushing for it to occur?
I've seeded quite a number of hints about the Pahn Kahl in the book. The first is Vahr and his rebellion, but there are a number of others. The first time that Siri assumes Bluefingers worships the Returned, he purses his lips in annoyance. We've got a lot of little hints like that that the Pahn Kahl are frustrated by their place in the empire. They controlled this land long ago; we discovered that from Hoid's storytelling.
It's well foreshadowed, but I still worry that it will be too surprising to people. This is primarily because I think that readers will just pass over the Pahn Kahl while reading. They're forgettable by design. Easy to ignore, and most of the other characters have trouble remembering that they aren't just Hallandren. They aren't an angry and vocal minority, like the Idrians. They're just there, or at least that's how everyone sees them.
One of my big goals for this book, however, was to have a good reversal for who is the bad guy pulling the strings. It's not the high priest. It's not the crafty god. It's not even the brutal mercenary. It's the simple, quiet scribe. It's one of the biggest conceptual reversals in the book. Hopefully it works for you.