From publisher blurb:
There are things that dwell in the Crypt, and some are Best Left Buried
Best Left Buried is a fantasy horror game where the monsters are scary and the players are scared. Within the Crypt, these adventurers will be beset by strange monsters, bizarre environments and eldritch magics, which will take them on their journey from fresh faced recruits to grizzled survivors.
This is a supplement for the main game, adding 30 pages of additional content to create more varied and powerful characters for Best Left Buried. It contains content found in the Deluxe Edition print version of the game.
Inside is:
Arcane, Devious, Holy and Martial advancements unlocked in high level play.
3 non-human Archetypes: Elves, Dwarves and Small Folks, and a short list of 6 new Afflictions for them.
Tables for random character generation
The same main rules for Advancements and Character Creation found in the Cryptdigger's Guide to Survival, so you don't have to flip between 2 PDFs while building a character.
While the Advanced Character Options contains lots of new content, this book won't make too much sense to you unless you own a copy of the Cryptdigger's Guide to Survival.