The Shifter Shard — L. Darby Gibbs

It's the simplest things that can throw you for a loop.

Young wielder Pratter agrees to travel to Carolan Faire to pick up an apprentice whose master died unexpectedly and bring him to the Chussen wielder school.

It seemed simple enough until he learned that wielders are being attacked, their powers of wielding the magic essence stolen from them. Before he can even get his first night's sleep in the dead master's house, someone enters through locked doors and attacks Jahl's friend Rouen.

By noon, no one is safe and anyone could be the assailant.

Read the second book in the Standing Stone series because the Sinister Sisters are more than a mountain named after a myth.