From publisher blurb:
Astonishing Races: Tiefling gives the tiefling a full-racial review and expansion, emulating the style of the “Core Races“ as detailed in books like the Pathfinder Roleplaying Game: Advanced Race Guide and others.
Astonishing Races: Tiefling aims to give players of the horned, demon-spawned humanoids immersive, world-neutral materials and support for almost any kind of play. Included are new and expanded options for alternate racial traits and subtypes, favored class options for all the base, core, hybrid, and occult classes, and three racial archetypes.
The book also has new racial rules for tiefling equipment, feats, traits, magic items, spells and more!
So if you’ve ever wanted to play a tiefling that can change her shape, The Soulsliver archetype, a twisted soul looking for redemption, or just love tieflings, Astonishing Races: Tiefling is the book for you!