You have arrived in the depths of the Praetorium, and Gaius has taken the helm of the Ultima Weapon.
How to Unlock
A Note About Unskippable Cutscenes
This trial is one of a small number of duties in Final Fantasy XIV that contains unskippable cutscenes. Because of this, this trial may take longer to complete than other trial. During these cutscenes, the dialogue will advance automatically and cannot be skipped.
Titan will cast Earthen Fury, which damages all players.
Geocrush places a proximity indicator in the area. Get as far away from it as you can, to reduce the damage that you take.
Titan will cast Landslide, a fiery line attack. The Ultima Weapon will then cast Landslide.
Weight of the Land covers the area in alternating circle attack markers.
Granite Interment traps all players, and the Ultimate Weapon will begin casting Earthen Eternity. Eventually, you will be freed and the battle will continue.
Garuda will cast Aerial Blast, damaging all players.
Eye of the Storm is a donut attack around the edge of the area. Garuda will go to an edge and cast Mistral Shriek, a large circle attack centered on her. Avoid this by watching where Garuda goes, and move as far away from her as you can.
Vortex Barrier makes the Ultima Weapon invulnerable, and it will begin casting Headsman's Wind. Eventually, the barrier will disappear and the battle will continue.
Ifrit will cast Hellfire, damaging all players.
Radiant Plume creates circle attack markers throughout the platform.
Vulcan Burst knocks back all players from the center. This is followed by Radiant Plume circle attack markers around the edge, so you should quickly move back into the center after you are knocked back, or you can use a knockback-prevention move such as Arm's Length or Surecast before Vulcan Burst finishes casting.
The Ultima Weapon begins casting Radiant Blaze, which covers the entire area, but eventually this is stopped, and the battle continues.
After the Ultima Weapon has taken a certain amount of damage, there will be an unskippable cutscene.
Homing Lasers is a high-damage attack on the player highest in the enmity list.
Magitek Ray casts three line attack markers in sequence, one straight ahead, and the other two at angles.
Homing Ray marks all players with circle attack markers. Don't overlap other players with your circle.
Tank Purge damages all players.
Aetheric Boom is a knockback attack. You can use knockback-prevention moves such as Surecast or Arm's Length to avoid it.
Two pairs of orbs, tethered to each other, will appear. Players can absorb these orbs to prevent them from colliding with each other.
Citadel Buster is line attack indicated by a glowing green light. To avoid this attack, don't be in front of the Ultima Weapon when it is casting Citadel Buster.
Untargetable Magitek Bits will sometimes appear. They will turn to face a certain direction, then attack with line attacks in the direction that they are facing. Watch the Magitek Bits to see which direction they are facing, and move to avoid being in front of them.
Sometimes, proximity indicators will appear in the corners. Go to the center of the area to minimize the damage that you take from them.
Eventually, the Ultima Weapon will start casting Ultima. A DPS player should use Limit Break, and all players should do as much damage to the Ultima Weapon as possible, as quickly as possible, to defeat the Ultima Weapon before it can finish casting Ultima. Eventually, your Limit Break gauge will be completely filled, so a DPS player should again use Limit Break as soon as this occurs.
Completing the Quest
Defeating the boss will complete one of the quest objectives for the Main Scenario Quest The Ultimate Weapon.