7 books in series

Chrestomanci

Chrestomanci is a 8-book series with 7 released primary works first released in 1977 with contributions by Diana Wynne Jones.

Charmed Life
The Lives of Christopher Chant
Witch Week
The Magicians of Caprona
Stealer of Souls
Conrad's Fate
The Pinhoe Egg
Mixed Magics