Massive, multiheaded beasts, hydras are fearsome Magical Beasts. Though similar in appearance to dragons, these rare megapredators are not intelligent creatures; there is no reasoning with a hydra or its boundless hunger. Hydras are strongly magical, with powerful regenerative capabilities and elemental breath weapons.
The Party encounter a druid who used the guise of a cryohydra in battle. In this form, she slew Hasan al-Husam, though he was saved from the brink of death by Lyr.