From publisher blurb:
We are proud to present Racial Guide 3: Races of Darkness! This installment focuses on new races found primarily in and around the underdark. The book is loaded with lore (politics, geology, culture, etc), new mechanics (darkness as a terrain type for example), 15 deities (ever wonder what a troll deity was like?), 15 new racial weapons, kobold line guns (and siege cannons), 17 new feats, and...
Included:
Arachno (Drider)
Dark Folk
Derros
Kabouters
Kobolds: Jaksear
Kobolds: Svarik
Pechs
Sunkids
Trolls
We’ve also got your class needs covered!
Ancestral Bloodline Sorcerer: Mix your power with those who came before for immense flexibility!
Black Widow: A cursed prestige that mutates you into a spider abomination!
Bloodseekers: Drow anti-paladin archetype for followers of the Spider Queen.
Cave Stalker: A underground svirfneblin ranger archetype for stealth experts of all sorts.
Dark Hunter: A duergar ranger archetype that overcomes their racial weakness to sunlight!