Read the last Rangers book by JDL Rosell, and -- egh. I've said before that with each series, Rosell gets better, and that's true, but I admit this one was dire.
There are good points: A much better job at giving Leiyn a personality than previous books, which is neat. The ongoing problem of 'there are just too many characters in the main band' is not quite as pronounced here, albeit at the cost of most of them blending into the background. I respect the book having the balls to kill off Leiyn's love interest in the final battle and have her stay dead (and while you could probably claim Bury Your Gays there, I think that'd be unfair when none of the straight romances fare any better).
The key problems, though, are: -- Nothing really happens for a big chunk of the book. Not all of it! The first 20% has a prolonged 'Leiyn in prison' section, which is narratively very slow but does serve the fairly significant plot purpose of forcing Leiyn into a situation where she has to become the host of a vengeful dead god that will slowly kill her. The latter 25% is the final battle, and stuff is happening there. Everything in between that, though, is just a whole lot of nothing, or events which don't really amount of anything.
-- As a continuation of the above, it has the problem a lot of fantasy books have, which is The Travel Issue. Fantasy and sometimes sci-fi has a bad tendency to devote a significant amount of time to travel, instead of just going "The characters traveled to [X], it took [Y] time," and jumping straight to the interesting stuff happening at the destination, or jumping from one stop on the journey to another in which interesting things happen.
Let's take two other books I've read recently as examples. Cursor's Fury, the third Codex Alera book, has a lot of traveling nominally in it -- Isana travelling to Ceres, Amaya travelling to Ceres and then to another lord's fortress, Tavi travelling for a month to his Legion and then that legion travelling. Exactly none of this travel is shown, bar a single chapter of Tavi doing combat training on the way to his Legion. This is fine! I don't need to see these characters travelling through the wilderness!
Or Six of Crows. I think roughly about one act of that book takes place on a ship between Ketterdam and Fjerda, our travel section of the book. What is happening in that section, though, is that a major character is being treated for life-threatening wounds. That is our 'interesting thing that happens,' and the narrative focuses in on that and tells us almost nothing about the actual journey.
-- Sharo's plan feels extremely ... woolly. He wants to consume Leiyn's soul, but it's not clear why save that she has a powerful soul and it'll make him more powerful. I actually almost expected that Leiyn becoming host to the aforementioned vengeful dead god was part of his scheme and that he intended to use her to devour that, but no, that was not the case. There are vague notions that he maybe wants to rule the world, and maybe wants to wipe out humanity, but nothing really happens in those directions apart from him invading the colonies.
All of this serves to rob his plan of any tension. Let's say your villain wants to rule the world: The narrative needs to build to some kind of masterstroke that would if completed make them the world's ruler, that would fundamentally and irreversibly change the world. Or the reverse: Maybe your villain doesn't need to do anything because they already rule the world. In that case, the narrative needs to build to some kind of action on the part of the protagonists that would stop that being the case, and in doing so irreversibly change the world.
What we have instead here is 'Sharo wants to rule the world (and maybe wipe out humanity), and he basically rules a lot of it already, and his plan would see him rule a bit more of it but not all of it.' That's nothing, man.
-- The big plot twist is that the sun is a titan ala the ones that have been present throughout the series as manifestations of nature. The problem is that a) This was obvious the moment it was brought up that someone called on the sun's power to attack a titan, and b) It changes nothing for the characters.
It's annoying that my primary emotion for a significant part of this book was just 'boredom.'
















