Spectres of the Last War
Tieflings are descended from the long dead humans of the nation of Ohr Kaluun, whose mastery of arcane lore led them to expand their power by making pacts with devils. After the Inspired of Riedra conquered their kingdom, the survivors fled elsewhere in Eberron, with many tieflings finding themselves in Khorvaire. They still bear the marks of their ancestors’ infernal bargains—horns, tails, and glowing eyes.
Tieflings do not manifest Dragonmarks.
Mechanically, tieflings get +2 to Charisma and +2 to Contitution or Intelligence. They also have low-light vision, bonuses to Bluff and Stealth, fire resistance, and abilities related to bloodied enemies and revenge after getting hit.