By clearing this dungeon, the player will obtain 200 Allagan Tomestones of Poetics. The cutscenes in this duty were made unskippable in patch 4.2.
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.
The party faces off against Gaius van Baelsar, the beginning of the final boss sequence.
This fight is relatively simple but be prepared for a lot of running because Gaius will teleport around the area fairly often.
Gaius's basic attacks won't hit too hard in the early going, as he goes easy on the party and will use Innocence, which strikes as a cleave for roughly 800 damage on a tank. After taking off about 5% of his Gaius will move the fight to the next phase.
The next phase starts with Gaius applying a bleed effect using an unnamed ability, dropping an AoE zone of blue fire and use Sentence to lunge after random players dealing moderate damage and heavy Knockback. He will also fire random shots at the party with his Hand of the Emperor and Heirsbane abilities, inflicting moderate damage. He will also begin to teleport at random, reseting his enmity and placing himself in melee range to attack the parties healers and ranged DPS. Upon teleporting he will leave the zones of blue fire, so make sure not to run through them.
His most powerful abilities are Judgement: large radius red circle AoE, which will strike for about 1800 damage to anyone caught in the blast radius and a Terminus Est which will create a blue X of energy in the air, which will hang for several moments before firing straight forward in a line.
The fight will end when Gaius's health is reduced to 20%, leading into the fight with Ultima Weapon.
The fight against Ultima is divided into two separate battles with a break in between them. During the first fight the weapon has the powers of Ifrit, Titan, and Garuda and Gaius will summon them to preform some of their most powerful attacks. This battle requires a lot of focused, quick movement to avoid major damage, and healers will likely be hard pressed the entire time. Ultima Weapon can end this fight quickly with its multitude of AoE skills.
During this battle players will receive repeated healing from Hydaelyn, the goddess of light. When this happens, the entire party will heal upward of nine-thousand health. Ultima will use several abilities, such as a basic energy sphere attack on the tank and Magitek Ray; this laser will mark a line of green energy across the arena, which explode a moment later and Ceruleum Vent, an AoE focused on itself with a radius of approximately ten meters. This will hit lightly armored characters for five hundred damage and will be cast repeatedly, so melee damage may suffer if they are forced to retreat for breathing room.
Shortly after the fight begins Ultima will begin using Geocrush (Titan's skill), Vulcan Burst (Ifrit's knockback), and Aerial Blast (Garuda's AoE). Throughout the fight, These abilities will often be used in rapid succession, but the damage is much weaker then when fighting the Primals.
The most damaging ability for this phase is Aerial Blast, but the party will get a message five seconds before it is cast, at which point the party will take no damage while Ultima Weapon prepares the ability, giving the parties healers ample time to top off the party and prepare for healing afterwards.
Phase 1 ends at 66% when Ultima Weapon loses control of Garuda, which stops it from casting Aerial Blast. The party will then receive a large heal from Hydaelyn.
Ultima will use Radiant Plume and Weight of the Land, the floor-based AoE attacks that Ifrit and Titan used, as well as continuing to use Ceruleum Vent. Players will need to remain near the outer part of the map, as they will have to move back and forth very quickly to avoid the massive AoE damage that these output. Radiant Plume will alternate exploding in the middle of the arena, then the edges of the arena. There is a sweet spot between these areas where minimal movement is required, though still necessary. This will likely be one of the most challenging parts of the fight for healers, and they should be prepared to have a DPS character die if they don't move fast enough. Weight of the Land deals high damage, but party members need to focus on surviving Radiant Plume which will do more damage. Battle raises are not recommended, but they are possible during this phase.
At roughly 33%, Titan will physically appear and use Earthen Fury, tearing loose from Ultima Weapon. Hydaelyn will heal the party immediately after this AoE, signaling the beginning of Phase 3.
After Titan is released, Ultima is left with only Ifrit's stolen abilities to use, which will reduce the damage quite a bit. He will still use Ceruleum Vent and Radiant Plume over a large area, but these are much easier to dodge without having to worry about Weight of the Land. However, the pattern is not so simple as dancing between plumes. Ultima still casts Radaint Plumes in the center, then on the edge of the arena, but it can also cast it in a cross-like pattern; a large plume in the center, with four more plumes at each 90 degree angle of the central plume. This will leave small areas between the outer plumes as safe spots, but not for long, as the follow-up is simply casting Radiant Plume again in the center, and the once-safe spots. Simply hitting a Level 3 Limit Break at the end should be enough to finish off part one of this boss, and lead into the second, more brutal fight.
In the second fight, Ultima has lost the abilities of the Primals but Lahabrea has unlocked the more powerful weapons lurking in the machina. He will continue to use Ceruleum Vent and will now fire Magitek Ray much more frequently. Ultima will also summon Magitek Bits. These small machines will use their ability Assault Cannon to fire lasers across the arena and should be killed by the DPS players immediately. Each time Magitek Bits are cleared, the amount summoned next time Ultima casts it is doubled.
Periodically, a "ripple" effect will be seen on the ground signalling Ultima's Freefire attack. All players must position themselves as far from the epicenter of the attack as possible. After a few seconds, an airship will crash and explode for damage that increases the closer players are to the epicenter. Those who fail to move properly will suffer heavy damage and most likely suffer an instant KO.
The next phase will begin when Ultima Weapon's health has been reduced by half.
Ultima will continue to use the same attacks from phase 1 and will use a new attack called Tank Purge. Tank Purge is an unavoidable AoE that does a large amount of damage to the whole party. Healers will have to heal the Tanks immediately before Gaius can take them out with Ceruleum Vent.
Ultima will also begin to use Aetherplasm, a green ball of energy which will follow one player slowly before exploding so players should take care to avoid them before they detonate.
At 10% health the fight will move to the final phase.
At approximately five to ten percent health the Ultima Weapon will warp to the center of the arena and begin casting Ultima. During this time there will be no outgoing damage. Therefore all players should immediately begin attacking with all available abilities and cooldowns. Though the cast time on Ultima almost thirty seconds should it finish casting the party will be instantly killed. While not required, this is an optimal time to use a limit break. As long as the entire party is alive there should be little issue finishing the Ultima Weapon off before it finishes casting.
After the Ultima Weapon is defeated, the party has a break and then faces Lahabrea.
Lahabrea is notorious among fans for being an easy final boss, so much that The Ultima Weapon is often cited as the game's true final boss. Lahabrea's main offensive attack is Shadow Orb, which deals very low damage to a random party member. He can also create pools of dark energy that detonate called Sea of Pitch, and knock back enemies in melee range with Grip of Night. His most powerful attack is Shadow Flare, which he will only cast twice. The attack will strike the entire party, but never deal enough damage to KO an adequately equipped character.
All characters have the Blessing of Light status effect permanently cast on them, boosting their stats and regenerating their health. Therefore, losing the battle is virtually impossible, unless one deliberately avoids attacking Lahabrea at all.
"Penitus" plays throughout the dungeon. It contains Latin chorus and was composed by Masayoshi Soken.
The theme played while fighting van Baelsar is called "Bite of the Black Wolf," composed by Masayoshi Soken. It is an instrumental version of Rise of the White Raven.
Porta Decumana appears as a stage, and is the first stage representing Final Fantasy XIV.
As with other stages, it features a stage transition. In the beginning of battle, the stage will elevate upwards until it reaches the top, wherein flames and destruction will engulf the stage, referencing Lahabrea's use of the Weapon.
The Praetorium appears as the Battle Music Sequence for "Ultima".
The Latin term praetorium originally signified a general's tent within a Roman castra, castellum, or encampment.