The Summer Queen by Rochelle Hassan
As a new coven, Aziza, Leo, and Tristan faced evil and triumphed; now, all that’s left is to put their lives back together. But everything changes with the arrival of strange visitors to Blackthorn: the Summer Court, a nomadic community of Fair Folk from deep in Elphame. They’ve come to take back something that belongs to them - something Leo’s not willing to lose. Refusing to give up without a fight, he makes a risky deal with the Summer Court’s princess and regent. The challenge she proposes sends Coven Blackthorn into the farthest, wildest reaches of Elphame. But when you play games with the Fair Folk, even winning has a cost.