Wiki - Sinful Encounter
To embark on this quest seek out Galadrion the Magus in a castle south of Moonglow Felucca. He will send those who agree to assist him on an epic quest to gather effects of several of the peerless.
Travel to each of the peerless who hold one of the requested items. Return with one of each (toggled as a quest item) and Galadrion will combine them into an Essence of Pure Sin, which is the key to enter the Vault of the Sinner. Be warned, the Essence of Pure Sin will evaporate in 10 hours. If it is not used to enter the Vault within this time then it will be lost.
Vault of the Sinner
The Vault of the Sinner can be found on the world Omniporter under Ilshenar Dungeons. Adventurers will need an Essence of Pure Sin to enter.
Each player who enters the gate will be in their own instance of the Vault of the Sinner. Partied players will be allowed to enter the same instance.
Once inside players will be forced to battle, in order, the Seven Sins that have been imprisoned in the Vault. Defeating all seven sins will grant a chance of a special artifact drop. Galadrion the Magus wears many of the rewards himself, a human only gear set and a talisman.
The Vault of the Sinner may only be entered once per 8 hours.