From publisher blurb:
It's Good to Be Bad
Tieflings survived brutal wars and fiendish pacts to become what they are today: sinister scions of a shattered empire living on the fringes of civilization, fighting for everything. Only the best of their kind would dare call themselves heroes, and fewer still have the wherewhithal to conquer the evil that haunts them. If you want to play the ultimate tiefling hero, this book is for you.
This Dungeons & Dragons expansion of the Player's Handbook core rulebook explores the mysteries of the tieflings. It presents players with exciting new options for their tiefling characters, including unique racial feats, paragon paths, and an epic destiny. This book also includes ways to flesh out your tiefling character's background and personality.