"You might want to think twice before you try to use a man's conscience against him. It may turn out he doesn't have one."
The Black Prism is absolutely a work of art. The world-building is exceptional, the magic is system complex yet easy to understand, and the characters are well crafted and masterfully developed. The real gem of the book though is the story itself. If i had to explain what "Epic Fantasy" means, The Black Prism would be my example.
A thing that characterizes all of Brent's work is the tremendous mix of fun and action, giving you a laughing fit at the most inappropriate of times. Worth mentioning is the juggling of several compelling and intertwining POVs with a straightforward prose, while the subaqueous qualities of the facture contextualize not only the characters but the society's structure as well.
If you call yourself a fantasy fan, The Black Prism should be the next book in your TBR list.