The Ultimaton is a large gray-black war machine created by the mechanist Lian, which was designed to replace the Avatar and all benders. Equipped with arms that mimic air, water, earth, and firebending, it is a formidable weapon. Lian, forced to work for the Fire Nation, envisioned the Ultimaton as a means to end the conflicts caused by benders in the world of the Avatar, and represents the pinnacle of Lian's vision of a new world order, where benders are replaced by powerful machines.