There are 4 Knight statues (Sir Xavier, Sir Anders, Sir Erondas, Sir Mastri) in the zone, you must move them down to the Chapel of Penance which has 4 alcoves, place each statue in the correct one (book nearby gives clues to location) ..
Ghosts of each Knight will spawn and move to the Temporal Chamber area, once all 4 ghosts are there, the center Sand Timer will become clickable, flip it over.
This will spawn mobs through-out the zone from destroyable gargoyle statues (destroy these otherwise you will get respawns - this also seems to kill all mobs that came from the statue)
Nameds will spawn in the original locations of the Knight statues:
Sir Loros Highgarden - puts alot of uncurable Arcane (divine dmg) on all players in range, run into Sir Xaviers ghost to get cured (you cant stand next to him - run in then away). He gets off his horse around 25% health (confirm?) and horse fights too. Horse dies when he does, though, so don't change targets.
Tsiet'Sozlt same as above - but he puts more uncurable effects on you (Elemental, Arcane, Trauma), run into Sir Anders for cure.
Gromkey same as above - but also spawns a pet as well - run into Sir Erondas for cure.
Arch-bishop Joltan same as above - but also puts curse on all, and will spawn a duplicate of one group member (that member will be stunned while the mob double is alive) - run into Sir Mastri for cure.
a chest will spawn in the Chapel of Penance - key drops from a phantasmal drunkard in the Great Hall
After all four nameds are down the room near the beginning of zone with the spider webs covering it will be open.
The Ghost of Gynok Moltor, Sir Xavier, Sir Anders, Sir Erondas, Sir Mastri will be standing at the stop of the room (Broken Stairs). Hail Gynok and Sir Xavier, Sir Anders, Sir Erondas, Sir Mastri will run to the 4 corners of the room.
Then Gynok will run down the stairs and kneel down and The Eidolon of Depravity will spawn just in front of him. If you are far enough away he will not engage until you pull.
Watch for "You've turned against him, you've all betrayed him, die!" when you see this he is immune to all damage. You must pull The Eidolon of Depravity over to one of Sir Xavier, Sir Anders, Sir Erondas, Sir Mastri this will make it so that The Eidolon of Depravity can be damaged again. (This will end up killing the ghost you pulled him to)
The trick to this fight is that you must do enough damage be before he becomes immune and you have him kill one of Sir Xavier, Sir Anders, Sir Erondas, Sir Mastri. Once they are all down you have about 45 seconds. If The Eidolon of Depravity is not killed by then he will run over to Gynok once he gets to him he will despawn and respawn as Gynok Moltor and Epic x4 mob.