Vegnagun's Body is a boss in Final Fantasy X-2. It is the third battle in the series against Vegnagun. Nooj and Gippal originally set out on defeating it with help from Leblanc, but are beaten themselves, leaving the battle to Yuna's party to fight.
When using the Dark Knight, two uses of Darkness kills both arms as well as deals a hefty amount of damage to the body. Once the arms are gone, the party should hit the chest with the party's strongest attacks. The arms will regenerate, but can be killed off easily.