There are 4 Knight statues (Sir Xavier, Anders, Erondas, 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).
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.