According to Polish publisher of the Magisterium series by Holly Black and Cassandra Clare, the books will be titled
MAGISTERIUM I: THE IRON TRIAL
MAGISTERIUM II: THE COPPER MASK
MAGISTERIUM III: THE COSMOS BLADE
MAGISTERIUM IV: THE GOLDEN BOY
MAGISTERIUM V: THE ENEMY OF DEATH
Each book will be a telling of Callum Hunt's life from age twelve to seventeen as he comes of age in a world where child apprentices train to be warriors and dark magicians seek to defeat even death.