The Poppy War, The Dragon Republic, and The Burning God by RF Kuang (4, 5, 6)
Well I finished the series, rereading the first two before reading Burning God. Its a pretty good series, but not a great as I wanted it to be. The first book is fun but a somewhat disjointed mashup between magic-school and war-fantasy. The second book is largely forgettable unfortunately. The third book is much better than book 2, fleshing out the storylines that you care about and giving you more of that sweet drug-fueled-shaman-massacre that you want. It does drag on a bit, but there was no way to wrap everything up given the way things ended in book 2, and Kuang at least had the talent to pull it off.
The last part of Burning God is where it all comes together. The war ends in the way you would expect, but then there's still about 20% of the book left. What remains is a rare discussion about what happens after a war. Ruling a fractured, failing empire ravaged by years of total civil war. And then after all that, an ending that would do even Bakker himself proud. I have a deep appreciation for authors who stick to the story they are telling, ending it the hard way, and Kuang does just that.
I was pretty on the fence about the whole series but the ending solidified it as a very good series. Its got its flaws, but if you want a Chinese inspired, brutal war fantasy, with crazy magic, this is definitely something you're going to want to read.