The Magicians' Guild (The Black Magician Trilogy, Book 1) (Black Magician Trilogy, 1)

This year, like every other, the magicians of Imardin gather to purge the city of undesirables.

Cloaked in the protection of their sorcery, they move with no fear of the vagrants and miscreants who despise them and their work—until one enraged girl, barely more than a child, hurls a stone at the hated invaders .

.

and effortlessly penetrates their magical shield.