A Prophecy Fulfilled - The Music Freaks AU

When children reach the age of sixteen, they develop powers, the type revealed by a mark, a small circle, and the enclosed design showing the powers. Only some actually receive these powers, and their use is highly regulated with each child beginning training by the time they reach high school. A long time ago, there were seven casters, each immensely powerful, who had to save their home from a friend, corrupted by power. After casting a spell that would keep the corrupt caster in a coma for many years, they revealed a prophecy, one which prophesied the return of the casters in seven new casters, one of which would end up with the corrupted spirit of the long-forgotten casters broken friend.
When seven students realize they've been chosen by the prophecy, they wonder if they're strong enough to fulfill their destiny.