Blood of the Chosen By Django Wexler

Standing on opposite sides of a looming civil war, two siblings discover that not even ties of blood will keep them from splitting the world in two.

Four hundred years ago, a cataclysmic war cracked the world open and exterminated the Elder races. Amid the ashes, their human inheritor, the Dawn Republic, stands guard over lands littered with eldritch relics and cursed by plaguespawn outbreaks. But a new conflict is looming and brother and sister Maya and Gyre have found themselves on opposite sides.

At the age of five, Maya was taken by the Twilight Order and trained to be a centarch, wielding forbidden arcana to enforce the Dawn Republic’s rule. On that day, her brother, Gyre, swore to destroy the Order that stole his sister… whatever the cost.

Twelve years later, brother and sister are two very different people: she is Burningblade, the Twilight Order’s brightest prodigy; he is Silvereye, thief, bandit, revolutionary.