Black Hydra

The Black Hydra is an optional miniboss in Dark Souls found in Ash Lake. It is a much stronger version of the Hydra earlier seen in Darkroot Basin.

The Black Hydra will follow the player until it is destroyed, firing water projectiles from a distance or lunging its heads into the ground at a closer range. When the player moves to a location that would require the Black Hydra to be on the other side of the beach, it is capable of leaping straight over the land to the other side.

A glitch in Ash Lake (possibly fixed in the 1.05 patch) causes the hydra to occasionally attempt to move onto land and instantly die, giving the player the full reward; this is most likely to occur after resting at the bonfire near the Great Stone Dragon, as the hydra will not reset its position, but will forget the player's presence and attempt to move back to its original location.

Strategy
The Black Hydra, like its weaker counterpart, is best fought at close range, but it requires far higher stats to successfully block.

After blocking its lunge attack, simply hack away at its vulnerable necks. Destroying them all will kill the hydra, and as each falls, the number of attacks will diminish.