Like the cyclops race, the medusa's current state exists because of conflict with the gods. While the cyclops attempted to supplant the universe's deities, the medusa refused to become gods and were cursed for it.
Legendary Races: Medusa explores the physiology, habitat and society of this legendary race. Additionally this second volume of the Legendary Races series by Stefen Styrsky includes:
New alchemical discoveries unique to the medusa race
An eight level medusa racial class
Diffraction goggles to control the medusa adventurer's gaze
Half-medusa racial traits for the offspring of medusa and their humanoid consorts (complete with alternate racial traits and favored class options)
Sample medusa and half-medusa npcs using the new racial rules
A medusa bloodline for sorcerer characters
Variant snake hair rules for the standard medusa
Finally a snake-bodied template and three medusa-related creatures. The blood summoner medusa, more mythical gorgon and the medusa husk.