Melissa Caruso, from Orbit Books.
I really enjoyed the heck out of this book. The world building is fascinating and detailed, the magic system is internally cohesive and believable and the political machinations for power (very loosely based on the great dynasties of renaissance Italy and environs) are well wrought and complex.
This is a substantial book, 438 pages, but tautly plotted and it never dragged. There are several plotlines, well interwoven into an epic story arc. I was very surprised that this is a debut novel; the author has a very strong voice and a gift with dialogue.
Other reviewers have done a very good job of describing the plot and characters. I really enjoyed the lushness of the setting (which reminded me a lot of Venice) and the way that the fire mage Zaira was not easily won over. Her unwilling partnership with a 'handler' of a different class and background was organic and well written, it wasn't just a few paragraphs of whining and then besties forever.
There were several mystery subplots which were deftly handled and the denoument was exciting and perfectly paced. I'm really looking forward to the next installments.
I would not precisely classify this as YA. It would be appropriate for older YA readers, but also fine for any epic fantasy fans, whatever their age.
Four and a half stars, looking forward to what comes next!
Disclosure: I received an ARC at no cost from the author/publisher.