Bloodmoon:The Ritual of the Sun

The Story of Aevar Stone-Singer
Aevar was tired, for the Sun would only burn, and the Winds would not yet cool him, but he rested briefly in the shade of the Trees. His legs were weary and his eyes heavy, but he continued on, traveling to the Sun Stone. Again, the All-Maker spoke.

"The gentle warmth of the Sun is stolen, so now it only burns. Free the Sun from the Halls of Penumbra."

And so Aevar walked west, over the frozen lands until he reached the Halls of Penumbra. The air inside was thick and heavy, and he could see no farther than the end of his arm. Still, he felt his way along the walls, though he heard the shuffling of feet and knew that this place held the Unholy Beasts who would tear his flesh and eat his bones. For hours he crept along, until he saw a faint glow far at the end of the hall.

There, from behind a sheet of perfect ice, came a glow so bright he had to shut his eyes, lest they be forever blinded. He plucked the flaming eye from one of the Unholy Beasts and threw it at the ice with all his might. A small crack appeared in the ice, then grew larger. Slowly, the light crept out between the cracks, widening them, splitting the ice wall into pieces. With a deafening crack, the wall crumbled, and the light rushed over Aevar and through the Halls. He heard the shrieks of the Unholy Beasts as they were blinded and burned. He ran out of the Halls, following the light, and collapsed on the ground outside.

When he was able to rise again, the Sun again warmed him, and he was glad for that. He traveled back to the Sun Stone, where the All-Maker spoke to him.

''"The Gift of the Sun is the Skaal's once again. It will warm them and give them light."''

Quick Walkthrough
# Find and activate the Sun Stone.
# Travel west to the Halls of Penumbra and kill the Lightkeeper Grahl to retrieve the Eye of the Lightkeeper.
# Once you free the light, return to the Sun Stone and activate it.

Detailed Walkthrough
thumb|right|The Lightkeeper Grahl
The Sun Stone
The Sun Stone is located in the southeastern portion of Solstheim and is not near any notable landmarks so it may be more difficult to locate than the other stones. If you follow the Iggnir River south until it bends toward the east, and then head uphill toward the northeast, the Sun Stone is on the top of the moderately tall hill. Activate the stone to receive the message to go west and free the Sun from the Halls of Penumbra. The hall is indeed almost directly west from the stone and you can follow a small depression in the landscape to help you find it. The hall entrance looks like a snowy cave.

The Halls of Penumbra
Inside you'll find the hall completely dark, meaning a form of Light or Night Eye will definitely be handy. You'll encounter a number of Draugr, one by one and a few treasure chests. At a four-way cross, go left, then right at the next turn, and you'll receive a journal entry about a light source. Continue downward and eventually you should find a light source at the end of a tunnel that illuminates the figure of a frightening looking spiked creature, the Lightkeeper Grahl. This grahl is very fast and powerful, so try to use ranged attacks as long as possible and keep a few healing potions handy. Once the creature is dead, loot the Flaming Eye of the Lightkeeper from its corpse and activate the ice wall containing the light. The eye will destroy the wall and let the light free, brightening the cave. 

Once you free the light you will receive a journal entry to return to the Sun Stone. Return and activate the Sun Stone to complete this portion of the ritual.

Notes
There are three locked (50) treasure chests at dead-ends, with random loot including Nordic Mail, and four bags with 100 gold each. 
A safe way to kill the Lightkeeper is to jump on top of the chest near the four bags of 100 gold; it can not attack you when you are on these.
 
Quest Stages