With the magitek field now out of commission, the path to the Ultima Weapon lies open. While the Immortal Flames sweep Castrum Meridianum and suppress the remnants of the enemy garrison, you and your comrades must fight your way to the innermost sector of the Praetorium, there to locate and destroy the Ultima Weapon. Cid's airship, the Enterprise, will bear you to the stage of the final confrontation.
— In-game description
- As of patch 6.1, extensive changes to general progression have been implemented, and certain cutscenes have returned to being skippable. As such, the rewards have been reduced. For the prior version, see The Praetorium/Old.
- Secure the command chamber: 0/1
- Make for the Laboratorium Primum: 0/1
- Power and board magitek armor: 0/1
- Defeat Nero tol Scaeva: 0/1
- Defeat Gaius van Baelsar: 0/1
- Ceruleum Vent: Unavoidable raidwide damage that must be healed through.
- Prototype Laser Alpha: Four circle AoEs will appear from the center and move toward the outside of the arena.
- Prototype Laser Beta: Circle AoEs will be placed on every player, requiring them to spread out.
- Grand Sword: A cone AoE targeting a random player.
There is an electrical field on the outside of the arena, giving people the debuff Electrocution that deals damage over time until they leave.
- Spine Shatter: Tankbuster.
- Iron Uprising: A frontal cone AoE that knocks players back.
- Activate: Summons a Magitek Death Claw that tethers to one player and slowly moves towards them, knocking player back when it gets to them. The players not tethered should kill it.
- Augmented Shatter: A stack on a random player, followed by Wheel of Suffering centered on the targeted player.
- Wheel of Suffering: A circle AoE that deals damage to all players near the boss. Players should stack together then move out of the following AoE.
- Augmented Uprising: Nero will hop to one side of the arena and attack a large potion of the arena with a cone AoE that should be avoided.
- Augmented Suffering: Nero will jump to the center and cast a knockback attack. Players should get into the center to avoid being flung into the electrical field.
- Innocence: Tankbuster.
- Horrida Bella: Unavoidable raidwide damage that must be healed through.
- Terminus Est: Gaius will fire several blue, flaming Xs. After a few seconds, a line AoE blast comes from the X dealing heavy damage to any players in its path.
- Phantasmata: Copies of Gaius will appear on the long side of the arena and each cast Terminus Est, marked by flaming Xs. Players should move out of the way of their path by moving in between two of them.
- Festina Lente: A stack marker on a random player.
- Ductus: Three circular AoEs appear on the short side of the arena and move along the length of the platform.
- Hand of the Empire: Each player will be marked by an unavoidable circle AoE. Players should spread out to avoid excess damage.
At 5% HP, Gaius will summon 4 Phantom Gaius adds that must be taken out while he charges up Blade Energy for his ultimate attack, Veni Vidi Vici, which will instantly kill the party if energy reaches 100%.
- Heirsbane: Each Phantom Gaius will target a random player, dealing moderate damage to them.
- Ductus: The party will continue to be bombarded with this and Phantasmata as they battle each Phantom Gaius.
- Horrida Bella: After Veni Vidi Vici is withstood, Gaius will spam a higher damage version of this until he is defeated.