Luna suddenly realized she peaked in high school [despite never actually going to high school] so she fakes a bunch of documents to enroll herself in princess celestia's school for gifted unicorn but accidently actually enrolls herself in Professor X
"So uh," Luna leaned on Magneto's shoulder. "What's the school lunch around here li--"
She was banished to the moon a second time. Witnesses say that they saw her being dragged by her own crown.
idk I'm hardly familiar with the X-Men franchise