When Alex finds out he is Unwanted, he expects to die. That is the way of the people of Quill. Each year, all the thirteen-year-olds are
labeled as Wanted, Necessary, or Unwanted. Wanteds get more schooling
and train to join the Quillitary. Necessaries keep the farms running.
Unwanteds are set for elimination. It’s hard for Alex to leave behind his twin, Aaron, a Wanted, but he makes peace with his
fate—until he discovers that instead of a “death farm,” what awaits
him is a magical place called Artimé. There, Alex and his fellow
Unwanteds are encouraged to cultivate their creative abilities and use
them magically. Everything Alex has ever known changes before his
eyes, and it’s a wondrous transformation.
(emphasis mine obviously)
They have a war at the end of the book. The main character uses paperclip shurikens.