D20 Into the Black: A Guide to Below

Publisher Blurb:

Deep below the surface, a new world awaits. While the plants and animals of the lands above bask in the warm glow of sunlight, the wildlife and creatures that dwell in eternal darkness must find different sources for nourishment. Adventurers that seek lost treasures within this realm are advised to familiarize themselves with this environment, lest they themselves become food for one of the dark realm's many predators.

Into the Black details this underground realm, providing ecological details as well as new monsters, races, magic items, and other game-oriented materials that both players and DMs need to expand their games.