The Rivan Codex (thing)

In 1998 David and Leigh Eddings wrote a new book: The Rivan Codex, basically an appendix to both The Belgariad and The Malloreon.
It's divided into several parts.

1. The Holy Books (of the diverse gods)
2. The Histories (of the assorted lands)
3. The Battle of Vo Mimbre
4. Preliminary studies to The Malloreon
5. The Malloreon Gospels
6. A Summary of Current Events

In this book there isn't a lot of Character Building but it's certainly fun to read and a big help in understanding the world in which a young farmhand named Garion became Overlord of the Western Lands.