Hellfire by Mila Young,‎ Skyler Andra

Everyone pays a price with dark forces. Unlikely allies and betrayal. An unrelenting enemy.
Luna’s whole world teeters on the edge after her expulsion from the Guild of Shadows. No more magic school. No more home. No more family. Definitely no spelled walls or sexy guardians to protect her from the dark forces hunting her. And just because she need a kick in the guts, Cole, her protector and boyfriend, abandons her too.
With a runaway serpent by her side, she’ll fight the darkness seeking her power to control the supernaturals. But the snakes don’t play nice. They play dirty and their fangs sink deep. Luna’s going to be lucky if she lives to see another day after they’re done with her, especially when no one is who they seem.