Hydra

The Hydra is an optional boss in Dark Souls.

Location
A Hydra can be found in Darkroot Basin and at Ash Lake.

Description
The Hydra is a large sea monster with a body similar to a plesiosaur, but with tentacles underneath a shell-like structure, and several long necks and heads. Each head can fire blasts of water from a distance or lunge into the ground for a close range attack.

Strategy
The Hydra can be defeated by severing its heads or by targeting the main body and using ranged attacks.

As the player moves closer to the shore, the Hydra will almost exclusively use its head strikes. After it lunges toward the player, each head will bury itself in the ground for a short time, presenting an opportunity to sever its vulnerable necks. As each head is defeated, the spread of the Hydra's attacks will diminish, making it easier for the player to finish the job.

The lunge attacks can be blocked or dodged. Certain spots can be found where the heads will completely miss the player. If the Hydra's position doesn't change, these spots can be exploited throughout the battle.

Darkroot Basin
The Darkroot Basin Hydra rests in a deep pit beyond an otherwise shallow pond and hardly moves at all. Crystal Golems in the area can be damaged by the Hydra's water projectiles.

As the player approaches the Hydra at a distance from its front, the slightly elevated area on the left, from the player's perspective, is almost completely safe from the water projectiles; however, they are relatively easy to block. Although the player is relatively safe from health and stamina damage when blocking, the water projectiles can still deal substantial stamina damage through the shield.

While using a hit and run method, players can utilize the rock and tree near the edge of the water as cover from the water projectiles and head strikes. After the Hydra thrusts its heads into the ground, hack at one of the necks until the head is severed. The last head, which is usually inaccessible for melee players, will repeatedly swing over the deep water area, causing it to always miss the player. The head can be dispatched with ranged attacks. A few shots will quickly sever the head and defeat the Hydra. Alternatively, the last head can become accessible if the Hydra's position is shifted by running along the water's edge.

Trivia

 * In Greek mythology, the Hydra was a serpent-like, multi-headed water beast. For each head that was severed, two more would sprout in its place.