Sutan had a talent for magic, but learning at the Magic Academy didn't satisfy him, so he turned to the forbidden books in the library.
He secretly studied dark magic for two years and summoned the devil many times.
You'd better go eliminate the pests around Gaia's tree. Closely observe their deaths, as I need more information to prove their link to dark magic.
Gaia's tree exposed Sutan's study of dark magic.
Gaia sensed abnormal dark waves inside Ilya and informed me. If it hadn't, there's no telling how long Sutan would have gone on summoning evil spirits inside school walls.
I suppose Sutan feels Gaia's tree is to blame for the Magic Academy expelling him the the magic community ostracizing him.