Cryohydra/Pyrohydra (+2 CR): Variants of the standard hydra, the cryohydra lives in cold marshes or on glaciers, while the pyrohydra prefers deserts or volcanic mountains. A cryohydra gains the Cold subtype, while a pyrohydra gains the Fire subtype. Each of its heads has a breath weapon (15-ft. cone, 3d6 cold damage [cryohydra] or 3d6 fire damage [pyrohydra], Reflex half) useable every 1d4 rounds. The save DC is 10 + 1/2 the hydra's HD + the hydra's Con modifier. Although fire attacks cannot prevent a pyrohydra's neck stump from growing new heads (since it is immune to fire), 5 points of cold damage does. Acid works normally on both hydra variants.