Monster Geographica: Underground is a 200-page pocket reference packed with 200 monsters from over a dozen different sources (both converted 3.0 and selected 3.5 monsters). Conveniently organized by challenge rating, this affordable resource of underground monsters is perfect for random encounters, adventure building, and campaign design.
Look for other titles in the Monster Geographica Line: Marsh & Aquatic, Forest, Hill & Mountain, and Plain & Desert.