Online:Light from the Darkness

Quick Walkthrough
# Retrieve the Light of Meridia from underneath the tree.
# Collect and place the three crystals.
# Destroy the two receivers binding the Ayleid King by rotating crystal prisms.
# Talk to the king.
# Enter the portal to the Hollow City.
# Enter the Fighters Guild Training Grounds.
# Talk to the king.

Detailed Walkthrough
thumb|right|Laloriaran Dynar imprisoned

Meridia's Light
When you first arrive, a projection of King Laloriaran Dynar will appear and ask you to retrieve the Light of Meridia in the front room.  It is underneath the large tree to the left.  You can move one of the roots to get in, or go around the back, where there's a small gap you can fit through.

The Crystal Puzzle
Enter the Lightless Oubliette tower. You need to recover three crystals: Lifeshadow, Mindshadow and Flameshadow Crystals. 

The Mindshadow Crystal is at the south end of the room, in the library. Take the red crystal at the southernmost end, then use the library gate switch for a quick way back into the main area.

The Flameshadow Crystal is inside the Frozen Alcove. Take the red crystal from the end of the Alcove. Once you do, the Frozen Alcove will begin to melt as lava seeps in through the floor.

The Lifeshadow Crystal is at the north end of the room, in the garden. Take the crystal at the bottom of the stairs, then use the library gate switch at the top to exit quickly.
 
From left to right, place the Mindshadow, the Flameshadow and the Lifeshadow Crystals. You can place the crystals whenever you want; you don't have to collect all three, then place them.

After the crystals are in place, enter the Ayleid King's prison and set him free.

The Prism Puzzle
Activate the first crystal prism to the left. Follow the light beam to the last crystal, the third lit one, and press it three times. Press the crystal that lights up five times. Repeat this process of activating the last lit crystal until the next one lights up until all the crystals are lit, and the prompt destroy the north receiver is complete. 

Next, you need to do the same thing to the south receiver. Place the light of Meridia in the crystal prism in the southeast corner, then rotate the crystals around. For the second crystal from the southern receiver, make sure the beam of light is headed to the crystal closest to the receiver.

Destroying both receivers frees the King. Talk to him, then follow him as he limps to the eastern side of the room and opens a portal to the Hollow City.

The Hollow City
Enter the door to the Fighters Guild Training Grounds, then climb the stairs and talk to the King.  

Notes
The Light of Meridia can be used within the ruin to brighten the area. Passing near an Essence of Darkness will dispel the light.
It is possible to enter the Lightless Oubliette without having completed either of the Moonless Walk quests. If you do so, however, the Light of Meridia will not be there. You can still enter the darkened areas where the three Crystals are found, and fight the enemies here (you'll need another light source unless you want to stumble around in the dark), but you won't be able to retrieve the Crystals and thus unlock the main chamber.
After completing this quest, the Fighters Guild Training Grounds in the Hollow City will unlock, and King Dynar and any other Fighters Guild members you have rescued will be found there. (It is possible to get onto the grounds before this by climbing over the structures outside the eastern gate, but this is when you are supposed to be able to get in.)
 

Quest Stages