Brent Weeks serves up a complex magic system based on the colors of the spectrum and he does it in a story that unfolds in provocative ways. Magic users, called drafters, use their powers to turn light into various effects based on color. This magical system, known as Chromaturgy, allows multiple colors of light to be combined in interesting ways, and for each drafter to have different skills based on their personal color abilities. There are also meaningful downsides to using this power, which makes a person's ability to draft a mixed blessing at best. The color spectrum is not only fundamental to the magic system, but also the religious and political systems as well, and all three are at the heart of the conflict that unfolds. As each layer of the story is revealed it picks up in both momentum and complexity, and it rewards you for paying attention to the details.
The Black Prism - solid start to the Lightbringer series