The Hydra Lair is a landmark from the Twilight Forest mod. Hydra Lairs can be found in Fire Swamps, and Twilight Swamps. When a player walks close enough to the Lair, the Hydra boss will spawn and begin attacking. The Hydra will not leave the lair for any reason. The Hydra Lair appears as a Large Hollow Hill that has been stripped of all chests and mob spawners, and has been cut open to give the Hydra space to sit.