Urobolus

Urobolus is the final boss of Xenogears.

Description
After the defeat of Deus, Elly tries to force away the remains of Deus into space to avoid the Wave Existence's departure from destroying their planet. Fei follows in Xenogears, the only Gear still working. He is caught up in the Path of Sephirot where he encounters Krelian. As a final test for Fei, Krelian summons Urobolus, a form of Miang that appears similar to the original mother, with wings and a snake's tail in place of legs. Urobolus' attacks consist of a Fist Attack and Serpent's Tail. Due to the simplicity of the fight, it is considered to be more of a symbolic battle than a traditional final boss fight.

Lore
Urobolus is a mistranslation of Ouroborus which is a circular symbol of a snake eating its own tail. It is a Gnostic symbol and is considered a symbol for an eternal cycle.