Thanks to everyone here who suggested the Twenty Palaces series by Harry Connolly

Being such an Urban Fantasy fan, I still don't know how this series slipped my radar all these years. But because of the excitement over Iron Gate just being published I picked up the whole series and have been binge reading until today when I completed the latest novel. I love that Harry flips your expectations so that no bad guy is the same, no plot is cookie cutter, and I'm still wtf'ing over what happened in Iron Gate because it was yet again so different (and great!). The one thing I know is true: a predator might be different but a ghost knife is always +20 to cunning.