Immortalis

The Immortalis also known by its production code XDA-1002: Immortalis is a supermassive "new model" of the production line of the Magitek infantry developed by Verstael Besithia as its ultimate creation. It is the final boss of Final Fantasy XV: Episode Prompto

Appearance
The Immortalis has the appearance of a giant mechanical worm with several drill-like appendages on its "mouth".

Story
Verstael developed the Immortalis as a way to create the greatest weapon. It is not known when the production of the Immortalis began although audio logs suggest it took a considerable amount of time to develop as he had finished several projects, including the Barbatus while the Immortalis was still in development. Although likely financed with support from Emperor Iedolas Aldercapt in recognition to Verstael's progress, the researcher had other plans for the weapon as he himself had intended to use it as a means to make the world "feel his wrath" and that not even "Astrals would be safe" implying much sinister, personal motives behind its creation.

After Prompto Argentum is abducted and taken to the first Magitek Infantry development facility and provoked by Ardyn Izunia to look for the truth of his "home", the lost young man finds Verstael in a chamber with several clones of himself. Verstael begins to mutate into a Daemon while telling Prompto the truth behind his origins. Prompto rejecting this guns Verstael, killing him, but this caused his Daemonified to soul to be transferred to the Immortalis starting its activation. The facility begins to self-destruct and Prompto gets aid from Aranea Highwind who convinces him to protect his life despite still being in shock of his creation.

When Prompto and Aranea defeat the Barbatus in another facility, the machines announce the successful activation of the Immortalis. Prompto and Aranea confront the mechanical monstrosity with a snowbike armed with a machinegun with Prompto decided to be the one to put an end to Verstael's madness. As they travel the snow plain, Verstael's corrupted desires are voiced through the machine, intending to cause destruction at the world he believes denied him his "glory" and repeating his desire to make everyone kneel before his newfound might.

The Immortalis ravages through the landscape with its massive body as Prompto continuously fills it with barrages of bullets. The Immortalis in turn deploys beams of its own. Even after this tactic fails and the machine is seemingly stopped it begins to glow with daemonic aura before glowing in a red-hot light utilizing the bulk of its power. The Immortalis attempts to charge its power on the core in order to blast Prompto, but the repeated gunning interrupts the process. In a final desperate attempt it will try to engulf them but the core is destroyed, ending the mechanical abomination and killing Verstael for good.

Following this victory, Prompto decides to catch to his friends to help them and ready to tell them the truth. Ardyn watches Prompto from afar while humming the "Victory Fanfare".

Battle
The Immortalis is faced as the final boss of "Episode Prompto" it is fought while riding a snowbike although the player only has control of the machinegun. There are several phases to this battle although while riding on the bike the player cannot use items so they must persevere with caution.

The Immortalis can be damaged everywhere although attacking it on its frontal drill will deal the most damage. At first the Immortalis will move in zig-zag before moving to aim at the player itself. They must damage the Immortalis until causing it to explode to prevent it from ramming them. At this point the drills will begin to glow and shoot beams of its own back at the player. Since the player cannot perform evasive maneuvers they have to shoot at the drills in order to disable them. Repeated gunfire can also prevent some beams from hitting, although it is difficult to succeed unscathed. On its next phase the Immortalis will begin to glow and attempt to charge energy to attack the player, they must attack the core with a continuous assault in order to interrupt the charge as otherwise the blast will mean an instant Game Over if it connects. After half the Core's HP is depleted it will attempt to "eat" the player, so they must inflict damage quick to prevent this. Upon success the battle will end shortly after.