To unlock Cloud of Darkness (Chaotic), talk to the Wandering Minstrel in Tuliyollal as a level 100 combat class and complete the base Dawntrail main scenario quest.
Register for the duty in the high-end duty finder with a minimum item level of 710.
Trade in Clouddark Demimateria loot to Uah’shepya in Solution Nine for various rewards such as mounts, hairstyle, and armor.
The Dais of Darkness mount and hairstyle can be sold on the marketboard, while the other items are market prohibited.