Promise of Blood is what is known as "Flintlock Fantasy" which means it contains a world where guns (musket/flintlock era weapons) exist alongside swords and sorcery. This book introduces the concept of Powder Mages, who are gun using sorcerers that rely on gunpowder to fuel their abilities. Powder Mages are able to enter a powder trance by ingesting gun powder which allows them to manipulate and control bullets as they fly, or even explode nearby gun powder being carried by their enemies. It is a unique magic system and executed pretty well by Brian McClellan. That concept, combined with an interesting story arc, carries the series and make up for the characters which I found to be a little uninteresting as a whole.
The series starts at the end of a coup led by Field Marshal Tamas, who with his group of Powder Mages, has just ousted the King and killed off his royal cabal of Privileged Sorcerers. A mystery presents itself right away as each member of the royal cabal utters the same words as they die: "You can't break Kresimir's promise." Tamas calls on Inspector Adamat to help sort out what those words mean and this leads to a story that unfolds over 3 books involving multiple nations, armies, and even gods. The 3 books in the trilogy are Promise of Blood, The Crimson Campaign, and The Autumn Republic
The three main characters throughout the series are Field Marshal Tamas, Inspector Adamat, and the Field Marshal's son, Taniel Two-Shot. Taniel earned his nickname because as a Powder Mage he developed the ability to unerringly shoot two bullets at once from his rifle to kill two different people. In what is perhaps the most interesting story line of the first book, Taniel is sent off by Tamas to kill the one remaining member of the royal cabal who survived the coup. That person is Privileged Borbador, who was raised by Tamas and happens to be Taniel's best friend.
For audiobook fans Christian Rodska narrates all three books and is a good fit for the content. He wasn't my favorite narrator at first, but his narration of this series is well done and gets better over time.
