The Trials of Blackbriar Academy by Olivia Ash

I shouldn’t be here, and everyone knows it.
Blackbriar Academy is an enchanted school on a magical island, and everyone wants in. It’s a home away from home for the most advanced mages in the world—and only the absolute best of the best are given an invitation.
By some freak accident, I managed to get one.
If I pass the trials, I get to stay. With nowhere else to go, Blackbriar is my one shot at having a real life, and I won’t let anyone take this from me.
But there’s a catch.
It turns out the people on this island are being trained to hunt the darkness—basically, they’re being trained to hunt me.
To survive, I have to hide what I am. As a half-mage, I shouldn’t have any magic at all. And yet, my natural abilities are almost impossibly powerful—and incredibly illegal. Over history, magic like mine has corrupted the souls of those who were born with it. They’ve all gone dark—razing towns and murdering hundreds of thousands throughout history.
All but me, and I have no idea why.
As the trials get more and more challenging, it’s clear I’m being hunted. If I’m caught… I die.
At Blackbriar Academy, nothing is ever as it seems… but I have nowhere else to go.
Nothing, and no one, will stand in my way.