The Underworld calls! Can you resist its dark lure? Deep within the Underworld of 13th Age’s Dragon Empire lie adventure and treasure—as well as madness and death. But what is reward without risk? - The Book of the Underworld uncovers the secrets of this vast and mysterious realm, including: - The lands of the Underworld: the Underland, the kingdoms of the Hollow Realms, and what lies within the Deeps - The mighty dwarven city of Forge, rallying point for the inevitable war to reclaim Underhome - The domains of the Silver Folk elves, and their underground icons: She Who Spins in Darkness, and He Who Weaves with Joy - The threats of Malice, the Drowfort, and the four kingdoms of the Mechanical Sun - Forgotten gods, the gnome academy of magic, monsters, magic treasure, and more! You’ll also find rules for traveling in the Underworld—including ways to make travel montages more interesting (and hazardous!)—and advice for GMs who want to create adventures and campaigns set in the Underworld.