The Behir is a serpentine monster that can slither like a snake or use its dozen legs to move with considerable speed. A behir is around 40 feet long and weighs about 4,000 pounds. The coloration of a behir ranges from ultramarine to deep blue with bands of gray-brown. A behir often knows the common language of the region.

A behir is a particularly nasty subterranean beast with a crocodile’s head on a 40-ft long snake-like body with twelve sets of legs. These creatures move very fast and can climb vertically at half their speed. Their main method of attacking is to bite and wrap their body around their prey and squeeze. On the second round they can still bite but the held victim is now subject to 6 claw attacks. Every 10 rounds a behir can also breathe a 20-ft lightning bolt that does 4d6+24 damage unless a save vs breath is made for half damage. Occasionally (on a 20) a behir will swallow its victim whole.