The Mage’s War by CY Jones

Crescent Moon Academy may sound like a magical place, but it’s anything but. In fact, if you’re not on your toes, you might find yourself very dead. Because in this academy killing is encouraged and the more clever you are gets you extra credit.
Killing is no problem for me or my brother. In fact, we rather enjoy it, but what happens when the gorgeous heirs from the other founding families decide despite my family name, I’m more suited to be their prey? And then there’s this war I had no intention of fighting in, but fate did not bother to ask my opinion before tossing me in headfirst.
Light, dark; whatever you practice, you better be damn good at it because there’s always someone in the shadows waiting to prove they are better and there’s no such thing as too far when proving you are the best.