At this point does it even need to be repeated? Age of Sigmar is just SO much better at letting more than one faction matter. Like...it’s so much better than 40k in the lore.
Anyway; major spoilers below, you have been warned.
First things first; Morathi wins. Completely. She ascends to godesshood by fusing with Khaine, becoming Morathi-Khaine and she conquers Anvilgard successfully from the Stormcast Eternals.
For her the book is largely an out-and-out win (as far as she knows!)
I also enjoy small notes just about the abilities of the Khainites. To contrast with 40k again; in 40k a consistent problem in the lore is that the Space Marines are better than everyone at everything. They are simply the best at every single thing they do, there is no field where they do not utterly curbstomp every other faction in the lore.
By contrast, in this book, we do just explicitly get told, and shown, that Stormcasts just are not capable of matching the stealth capabilities of the Shadowstalkers. Stormcast attempts to breach the Eightpoints are described as consistently leading to high causalities with little learned from it. The Shadowstalkers, meanwhile, not only successfully infiltrate but are also the ones who learn, and expose, a scheme by Archaon to use the realmstone of the Eightpoints to force open the Realmgate to Azyr.
Another tidbit worth keeping in mind; we are almost certainly going to see the introduction of Malerion’s faction during the Broken Realms. After the final battle of Anvilgaard is won Morathi hands over the Stormcast Lord-Veritant who stood against her to some Corsairs. He is saved by ‘shadowy beings with leathery, bat-like, wings and red eyes’ who slaughter the crew and then leave, allowing him to try to find a way to warn the others of Morathi’s betrayal.
Then, finally; the reason for that ‘as far as she knows’ is because one big thing occurs in this book which none of the major players are aware of; Slaanesh has given birth to the ‘Newborn’ and it has found its way back to Chaos.
It appears this is effectively Slaanesh’s method of escaping, giving birth to a new form of itself which slithers from the Gloaming at the moment of Morathi’s ascension.
Anyway; I like it! A good first book, shows AoS’ ongoing commitment to allowing other factions to win things, and just in general glad Morathi wins!