A part of Sunset wanted to die the night of the Fall Formal. In a way she succeeded. There's a reason everyone says Sunset is like a completely different person afterwards.
After the events of the fall formal Sunset is alone and most of the school against her. Will she accept her new friendships are real and will she realize that there is someone who wants to make her family?
The elements of Harmony are able to turn magical beings of unequal power to stone, exile opponents to the moon! Using one against a possessed teenager may have been overkill?