Hydra

The  is the boss of the tier 2 dungeon, Spawning Nest.

Trivia

 * The boss room that contains the Hydra is referred to as Den of Hydra.
 * The only entrance of this boss room is located at the bottom of it.
 * In Greek and Roman Mythology, the Hydra is a serpent most notably known for having multiple heads.
 * The Hydra was used as the main example in the pixel animation guide on the official website.