"War Master's Gate" is the first book in series that breaks the usual pattern, but the things have come to a level where everything is epic and you can't separate magic and technology storylines. It continues the events immediately after last book, "The Air War". This means that the war for Lowlands and Collegium continues where it stopped, minus the focus on air duels - even though they still play a large role in this book. General Tynan tries for the second time to conquer the Collegium, but Warmaster Stenwold Maker has his own trick to throw at them, and this time, the air supremacy in on Bettles' side. Up north, General Roder was on a way to attack Sarn, but he is stopped by direct order and appearance of Empress Seda, who has personal interest in the forest that hides the Mantis holds Etheryon and Nethyon. Sarn also has a new Tactician, who will prove a menace for both Sarnesh enemies and allies. And in the forest itself, Cheerwell and Seda confront directly, in race to conquer the old and dark power, not suspecting that this power is there to guard something even more terrifying...
It's good thing that I read the previous book not so long ago, because the series has progressed so far that you really need to be familiar with rich setting and large cast of characters. Even so, some references to past events were blurry to me. As I said, the book continues immediately after the events in the last one, and it feels very much like it. Again we have a big focus on military, sieges, defense, air machines and so on. There are no much new inventions, but Tchaikovsky uses marvelously what he brought so far, and makes a very consistent and unique setting. On the side of magic, here we have as large upgrade as we had with technology in "The Air War". We learn much about history, see some direct uses of Moth and other magic, and see first evidences of a new player to come.
Plot is very complex, mostly because it is shown from so many POVs. Constant jumps are maybe a bit tiring, combined with short chapters - but at the same time it forces one to read on. There were lots of surprises throughout the book, especially because they came as surprises to the characters themselves (the Hornets, for example; or Empress' orders for Spiders). The book ends in several cliffhangers, like the fate of Che and Seda. Similar is with Stenwold Maker - his part look a bit obvious, but maybe it is the exact opposite. The ending is very strong and emotive; especially between Tynan and Mycella, and Eujen and Straessa. A great part of the book is the epilogue, with afterlife in Collegium, and first appearance of the Worm.
Characters are also phenomenal, both old and new. We actually don't spend much time with most of them, but because of fast POV changes it feels like we do. The number of character in series has grown much, even the important characters. At the beginning of the book we have a superb scene with Che, her first impact on the Ants, Mantids and rest. Tchaikovsky became great in presenting all sides of the conflict without playing favorites. When the fight is told form Wasp's POV, you are rooting for Waps; but when the same battle is told from Collegium's POV, then they are your favorite. Also, he is not afraid to really kill the characters. The fate of Mantis race was a very sad and powerful scene, and it was masterfully told from several side: the sadness, the anger, the fear! Also, again a nice moral ambiguity with Collegium and Sarn turning themselves to Wasps to defend from Wasps.
I can honestly said that with last few books, and especially with "War Master's Gate", this series became one of my favorites. Great battle scenes, both technological and magical; powerful and emotive scenes from both sides of conflict; and revelation that will shake the plot so far. An excellent book.