While I still have issues with the glossing-over of slavery, I'm overall pretty happy with this story. My initial concerns over the slow reveal of the magic system's intricacies are gone, and I'll agree that the author did it right; there's enough in place to make everything sensible, while still having lots of reveal in later books. I like the reversal of the Mass-Energy Equivalence equation as a magic system, and I look forward to seeing where this goes.