Instructions
First Basement
Go north toward the torch in the corner. Light the torch to open a passage and go through the passage that takes you down into the first basement.
Travel east to find an axe-wielding statue surrounded by torches. Light the torch facing the axe, causing the statue to turn and face another unlit torch; light that torch to make the statue turn again. Continue lighting the torches the statue's axe faces until all the torches are lit.
Go through the door to find three torches and one statue. Repeat the process you used to light the torches in Step 2 to open another previously closed door in the room. Go through this newly opened passage.
Travel east to find two more statues where the axes both point to a torch in the corner of the room; light the torch. Continue lighting the torches the axes point to, saving the torch in the center for last.
Go north and fight the Guardian Beast. You'll receive a Light Ring after defeating the Guardian Beast. Use Darkness, Fire, Thunder and Water attacks to deal higher damage to the beast.
Travel south and take the stairs to the second basement.
Second Basement
Light the nine torches in the room in the correct order. The torch that should be lit next is always the torch that all of the axes belonging to the statues are facing.
Travel east through the southern exit. Use the Light Ring to get through the shadow barrier. Continue traveling east until you reach another statue and torch room.
Light the northwestern-most torch. At that point, the statue turns like previous statues, but this one shows the lighting order for all the torches once rather than just turning each time you light it. Memorize the order and light the torches. Lighting these torches opens yet another door in the room.
Travel through the newly opened door on the north side of the room and head left. Charge the Light Ring along the way. A cutscene plays.
Third Basement
Light the torches the statue points to as in previous torch puzzles. However, this particular puzzle comes with a twist: some of the torches in this room are already lit when you enter. The torches that are already lit are meant to fake you out. When the statue points to one of these torches, go into the hallway outside the room just outside the wall that the statue is pointing at to find an unlit torch in the hallway; light these torches to complete the puzzle. As you light torches, the water in the room will subside, revealing a lower level.
Travel down the stairs in the lower level of the room and save your progress at the save point.
Fight the boss of the Purgatorium, Tamiel. You start by fighting two sets of Tamiel's sidekicks who are Sydonaist enemies. Fight the sidekicks with basic physical attacks until they fall. After beating the sidekicks, you fight Tamiel, who summons additional Sydonaists to the fight. Use Edge to focus on the minions with his powerful attacks while the rest of the party deals with Tamiel. After the minions are down, focus everyone on the main boss. Use Water and Thunder attacks on him, as he is weak against those elements. Keep your party's health points up with potions and healing spells so they can survive Tamiel's beam attack. Additionally, try to keep your characters far away from Tamiel when he starts using his beams.
Rescue Sarah and exit the Purgatorium after defeating Tamiel. Sarah joins your party after you return to Calnus.