Before the player can fight Chaos in Final Fantasy XII, a sidequest must be completed to obtain the appointed keys. Chaos resides in the Necrohol of Nabudis, but to open the chambers that lead to the boss fight, the party needs three medallions. The player must go to Nabreus Deadlands to trigger the scene with the nu mou Ma'Kleou, and then collect three fragments.
To get the Blackened Fragment the Wraith, White Mousse, and Orthros hunts must be cleared, and the player will receive the Blackened Fragment as reward for the Orthros hunt. The Dull Fragment is hidden in the Garamsythe Waterway. After obtaining the Sluice Gate Key (reward from White Mousse hunt mission), the player can work the Sluice Gate Switches in the waterway.
The player must first turn all the switches off (that means lights off) and follow the steps below:
- On No.11 Area Panel (that means light up the panel)
- On No.4 Area Panel
- Off No.11 Area Panel
- On No.3 Area Panel
- Off No.4 Area Panel
After the last gate is closed a click is heard and south in the same semi-circle area, on the ground, there is a glittering object, the Dull Fragment.
To get the Grimy Fragment the player must return to Rabanastre Lowtown and go to Old Dalan's place and speak to the nu mou known as Roh'kenmou. For Roh'kenmou to appear at Dalan's place, the player must have first spoken to Ma'kleou in the Nabreus Deadlands. Filo is around the South East area of Lowtown and mentions the kids are also looking for the medallion. In Rabanastre's central section, Southern Plaza, there is a "Curious Woman" looking at the fountain.
After talking to the "Curious Woman" the player should walk to the Muthru Bazaar and speak to the bangaa merchant just after passing the Clan Provisioner about the necklace to get the information, then head to the Magick Shop and speak to the "Sotted Imperial", the soldier sitting in the left corner, and choose the first option. Back in Lowtown the player should talk to Filo again, choose "Let's Go" with Filo for some events to get the last fragment, the Grimy Fragment.
Back in Old Dalan's place the player should to give all the fragments to Roh'kenmou and he will disappear.
In Archades the player can find Roh'Kenmu within the Magick Shop, looking for a medallion. In the Old Archades the player can find the Proper Gent sitting on a side wall in the eastern side of the Alley of Muted Sighs. He is Otto and he will give the Moonsilver Medallion, which the player must pass on to Roh'Kenmu at the Magick Shop.
After giving the first two medallions to the nu mou, the player must travel to the Muted Scarp in the Nabreus Deadlands and talk to Ma'Kleou, then head northeast and search for a hidden path. One can find it by going south from the Gate Crystal, following the upper wall west, and searching the northwest area of The Slumbermead for the path. This is also the place where Roblon is fought.
After obtaining the medallions, the player must head to the Cloister of Distant Song in the Necrohol of Nabudis, and use the Medallion of Bravery to open the Door of Horrors, and defeat the Humbaba Mistant. Next, the player must head to the Hall of the Ivory Covenant and use the Medallion of Love to open the Door of Loathing and bring down the Fury. The player must defeat Humbaba Mistant and Fury to change the Lusterless Medallion to the Medallion of Might, which opens the Door of Despair to fight Chaos in the central section.