This Mission is completed in the Titan’s Trials / Faultwarrens.
This Cie’th Stone for this Mission can be found in any of the “D” labelled sections of the map:
A new Cie’th Stone can be found in each of these areas after you have completed all of the other Missions at least once. Refer to the Faultwarrens Side Quest page for a map of the location.
This mark for this Mission is located at the “Titan’s Throne” area of the Faultwarrens.
Class: A
HP: 9,135,000
Attacus is one of the more challenging fights in the Faultwarrens. It has the following attacks:
Deprotect and 
Deshell and dispels up to six buffs from the target and removes up to eight debuffs from Attacus while also dealing heavy damage.There are three separate phases to this fight. The first phase, where Attacus will attack normally, followed by the second phase, where it will use the Unrelenting Blade/Concentrate combo, and the final phase where it will use the Peerless Blade/Meditate combo. In other words, as the fight progresses, Attacus will do more and more damage to your party members.
Despite the fact that Attacus will be constantly dispelling the debuffs that you apply to it, it’s still worth keeping up Deprotect, Deshell and 
Slow. Slow will reduce the amount of incoming damage while Deprotect and Deshell will allow you to inflict more damage which will help you get through that 9 million HP sooner.
There are two strategies you can use to get through this fight. Either play it more defensively and have your party switch to a paradigm with a 
Sentinel to try and absorb the damage coming from Concentrate and Meditate, or go on the all out offensive and try to bring down Attacus as quickly as possible, reviving players as necessary.
The video below demonstrates the all out offensive strategy. It will be impossible to Stagger Attacus with its 999% Chain Gauge, but it will take more and more damage as the fight progresses by virtue of the percentage multiplier going up with each subsequent attack, so be sure not to let the Chain Gauge drop.
Genji Glove
Bomb Core (x10)
Natural Selector
You will receive the Natural Selector achievement / trophy after you have completed all of the missions in the Titan’s Trials / Faultwarrens ending with Mission 51 - Attacus, the Soulless.
You will now be finished the this area and will be transported back to the start of the Faultwarrens. You can navigate back to the Titan’s Trials / Faultwarrens page but you are officially done with this area once you have defeated Attacus.
Titan’s Trials / Faultwarrens
A subset of Missions that take place in the Faultwarrens area that involve defeating enemies spawned by the mighty Titan fal’Cie.
End Game Side Quests
A full listing of the optional end game content including missions, side quests, farming tips and all of the available achievements / trophies.
Full Mission List
A list of all the Missions in the game.
