The Prince of Nothing series.

A very solid series, dense as fuck, with an intriguing way magic works. Just be aware that there can be a fair bit of talking in-between action scenes, there's a lot of time spent in political/religious discourse between characters.

Also, birds with human heads! A prostitute finding out who she slept with by the fact he literally has black cum! Too many scenes of people cleaning themselves up after taking their morning shit!