Ex Magica: Dikaió Book 1

Cursed as a child, the heir of the Matriarchy Mallory Knenne is supposed to one day lead a world founded in magic. However, the curse has robbed her of the most important Matriarchal duty: passing magic to the next generation. Along with her friends, Alex Nelson and Caleb Aiworth, Mallory must use her wits to defend those she loves against political rivals, stop her sister from taking her place, and overcome her curse.
But when the curse proves to be contagious and all magic disappears, Mallory and her friends turn to an ancient power to save their civilization. Will their gambit succeed, or will they unleash a fiery evil that engulfs them all?