Vegnagun's Head is the fourth and final part of Vegnagun that must be destroyed.
During this battle there is a time limit to defeat this boss, and when the time is up, or the party members are killed, Vegnagun will fire its cannon, destroying Spira and giving the player the bad ending.
Destroying the Redoubts makes this battle much easier as it prevents the Head from utilizing several of its more lethal attacks, but the Redoubts revive after a period of time. It is good to dedicate one character to healing while the others focus on dealing damage, preferably with either Dark Knight's Black Sky or Darkness ability, the Gunner's Trigger Happy, or any multiple-hitting or full-party attacks.
The Gunner equipped with Cat Nip strategy makes this battle much easier by dealing multiple hits of 9,999 damage. Equipping the Gunner with a Speed Bracer gives her a permanent Haste. Cat Nip and the Speed Bracer can be obtained by defeating the Black Elemental on the 40th Cloister of Via Infinito. This strategy only works in the original versions, as in the International and HD Remaster versions Catnip gives Auto-Berserk.
Another strategy is to go through all of the gates in Megiddo Garment Grid (obtained by going through all of the routes to the Farplane) and spamming Ultima and Flare, with an Alchemist on standby for Ethers and mixing Mega-Potions (Potion and Hi-Potion).
Pallida Mors means "pale death", which is how the Romans described their mythological personification of death.
Acta Est Fabula means "the play is over", supposedly the last words of Roman emperor Caesar Augustus.
Mors Certa means "certain death".
Nemo Ante Mortem Beatus translates roughly as "no one can be happy before their death".
Odi Et Amo translates to "I hate and I love" from the poem "Catullus 85".