Drawing Down the Moon - Steven Lee Climer - Bog

Ronan and her friends unlock the secrets of delivering vengeance on their tormentors with an ancient artifact found in Ronan's mom's mail. However, it goes beyond petty high school teasing and the trio begins doling out horrific punishments. When it goes too far and Ronan wants out, Lyda, the charming new student, gets in her way. Ronan must break Lyda's hold on her friends before they become the monsters hunting each other.