Trial of Thorns by Stacey Trombley

Only the most ruthless fae can win. And I have nothing to lose.
I am Caelynn of the Shadow Court, a countess banished to the human realm for killing a fae prince a decade ago. But when I get the chance to fight for a full pardon—I’ll face every regret and lost hope to earn it.
Including Rev.
For the first time in years I am allowed the chance to enter the world of wild magic to compete in this ruthless completion of blood and magic. But the hardest part of the trials won’t be the shadow-wyverns or mind twisting mazes. It’ll be facing those I’ve betrayed.
Especially Rev—the sexy Luminescent Court prince who hates me.
Only one of us can win, and Rev will do everything in his power to make sure I don’t make it out of the trials alive.
Because ten years ago, I killed his brother.
And Reveln never forgets.