Hydra

Hydras were a breed of reptilian magical beast that had anywhere from five to twelve heads.

Ecology
Hydras typically lived alone in fetid swamps and waterways and were generally always the most dangerous predator in whatever area they inhabited.

Combat
A hydra was an especially deadly monster, since every time a head was severed, two new ones grew in its place.

Behavior
A hydra was not very intelligent, about as much so as an animal. Hydras were usually neutral in alignment.

A pregnant hydra preparing to give birth would build a nest for this purpose. It dug a pit beside a pond or body of water, then lined it with sticks and weeds.

History
Scholars from Candlekeep believed hydras evolved from proto-dragons.

In the late 1340s DR, the explorer Hadley Erridge of Thunderstone in Cormyr suggested to his neighbor, the enterprising and prosperous farmer Del Geery, that he get a hydra to scare off the pests plaguing his crops. Geery agreed to finance Erridge's expedition into the Vast Swamp to capture a live hydra. Two months later, they returned with an adult hydra in an iron cage. Erridge released the hydra and it rampaged about the farm, scaring away all the animals within a few days. However, despite what Erridge said about the hydra returning to the swamp when it ran out of prey, it instead stuck around and began building a nest by the pond. The hydra was, in fact, pregnant. Outraged, Geery gave Erridge the sack then hired a group of warriors to slay the hydra. Afterwards, he hired the best rangers and wizards in Cormyr to help him discover the uses to which he could put a hydra carcass, intending to use every part of the beast and recover his losses. He was so successful at this new trade that he began to fund new hydra-hunting expeditions in the Vast Swamp. By 1367 DR, he'd earned a reputation and a fortune in the hydra trade.

Uses
The enterprising farmer and hydra-hunter Del Geery developed a number of useful agricultural products from the body parts of the hydra, as follows:
 * Hydra teeth could be used to fashion almost-unbreakable blades for hoes, plows, and saws.
 * A hydra's hide could be dried and made into warming covers for raspberries, blueberries, and strawberries maintaining the air around the plants at 70 °F (21 °C), extending the growing period deep into autumn. The hides broke down when the temperature dropped below freezing for two days in a row. Hydra hides were only effective on these three types of berry bush, not on people, beasts, or other plants.
 * Dried hydra tongues could be used to predict the weather when hung in the wind like a flag. If the tongue turned red, then the temperature was expected to rise by up to 10 °F (5.6 °C) in the next 24 hours. If the tongue turned green, then the temperature was likely to fall to freezing. If the tongue turned black, then rain was expected the following day.
 * Ground, powdered hydra bones were an excellent desiccant. Added to a small grain bin, a pound of ground bone would absorb all moisture and stop rot and mold.
 * A mixture of hydra fat and cornmeal made for an oddly useful rat poison. It was irresistible to rats, and they grew so fat they could hardly walk, and were easily caught or predated upon.
 * Finally, the head itself, when mounted on a pole in a field, would scare away birds and small mammals. It could be preserved for up to six months.

Subraces

 * Cryohydra: A relative of the standard hydra that was able to breathe frost from its heads.
 * Lernaean hydra: A relative of the standard hydra that was able to breathe poison clouds.
 * Pyrohydra: A relative of the standard hydra that was able to breathe jets of fire.

Appearances

 * Computer Games:
 * Baldur's Gate: Siege of Dragonspear
 * Hillsfar
 * Secret of the Silver Blades
 * Novels
 * Brimstone Angels: Lesser Evils
 * Mortal Consequences
 * King Pinch (mentioned)
 * Stone of Tymora (mentioned)
 * The Fallen Fortress
 * The Halfling's Gem
 * The Shadowmask
 * Under Fallen Stars (mentioned)