Hexborn. A Thorne Witch Novel, #2

Witch by birth, warlock by trade. Adeline Thorne is a witch. The magic living inside her is not. And time isn't on her side. The warlock magic coursing through her veins is volatile, incompatible with her witch blood, and growing more unstable by the day. Witches don't trust her. Warlocks fear her. Except for one. Luke Churchwell is a powerful warlock who wants to help her master the magic threatening to destroy her.
But Adeline's failing health makes every lesson a gamble, and his desire for her may take them both down. Far beyond the city, the hexborn, a secretive magical race, are tracking a killer. Their guide: a young girl's terrifying psychic visions. And the trail leads straight to Adeline. When the hexborn and Adeline collide, they discover a chilling truth: a lone hunter with extraordinary power has been unleashed upon Adeline by someone determined to see her dead.
Time is running out. The hunter is closing in. And the only thing more dangerous than the enemy at her door is the rogue guild that created him. Fans of Kim Harrison's dangerous magic, Ilona Andrews' fierce heroines, and Deborah Harkness's journey of magical awakening will be captivated by Hexborn.