The Outcast Mage — Annabel Campbell

A mage bereft of her powers must find out if she is destined to save the world or destroy it in this glittering debut fantasy perfect for fans of Andrea Stewart, James Islington, and Samantha Shannon.
In the glass city of Amoria, magic is everything. And Naila, student at the city's legendary academy, is running out of time to prove she can control hers. If she fails, she'll be forced into exile, relegated to a life of persecution with the other magicless hollows. Or worse, be consumed by her own power. 
 
When a tragic incident further threatens her place at the Academy, Naila is saved by Haelius Akana, the most powerful living mage. Finding Naila a kindred spirit, Haelius stakes his position at the Academy on teaching her to harness her abilities. But Haelius has many enemies, and they would love nothing more than to see Naila fail. Trapped in the deadly schemes of Amoria's elite, Naila must dig deep to discover the truth of her powers or watch the city she loves descend into civil war.
 
For there is violence brewing on the wind, and greater powers at work. Ones who could use her powers for good… or destroy everything she's ever known.