For those who haven't accepted the 'Evidence quest' you might want to do so before going to meetup at Luna Faiground stage area (just to save some time)
From Stratics - The Citadel ...
To enter the Citadel you must be on the 'Evidence' quest given by Sarakki the Notary in Britain. To gain access to the Peerless boss, Travesty, you must gather three keys from the Black Order Ninjas in the dungeon and drop them on the table in the central room. This will result in three master keys that will take you to the peerless area. The Citadel Route Finder