Skyrim:Unearthed

Quick Walkthrough
# (Optional) Read ''Ahzidal's Descent''.
# Investigate Kolbjorn Barrow and speak to Ralis Sedarys.
# Agree to help Ralis fund his excavation by donating 1000 gold and wait for a message from him.
# Visit Kolbjorn Barrow and defeat the draugr.
# Find a way deeper into the barrow, and then speak to Ralis again.
# Donate 2000 gold to fund the excavation of Kolbjorn Barrow and wait for another message from Ralis.
# Return to Kolbjorn Barrow, clear the draugr, and search for missing miners.
# Speak to Ralis, fund 3000 gold to his excavation, and await another message.
# Return to Kolbjorn Barrow and clear the draugr.
# Speak to Ralis, fund 5000 gold to his excavation, and await another message.
# Return to Kolbjorn Barrow and locate Ralis.
# Defeat Ahzidal and confront Ralis; decide what to do with him.

Detailed Walkthrough
A Strange Partnership
Just northeast of the Old Attius Farm is Kolbjorn Barrow. Outside Kolbjorn Barrow is a lone Dunmer named Ralis Sedarys. Go up and talk to him and he'll explain that he is a treasure hunter and has come with news that he has located a treasure in the barrow, but he cannot afford to excavate it alone and requests a donation of 1000 gold, with a promise of a share of any treasure discovered.

First Visit
A few days after you give him the money, a courier will give you a note about the barrow. Head off over to the barrow, and Ralis will explain that the draugr have been disturbed, and they have killed all the miners. He asks you to go in and kill the draugr and then find a way further into the barrow. After you have killed the draugr, take the Skull off the altar to open the next area, Go into the next room and pick up the Ahzidal's Boots of Waterwalking. (If the skull has been knocked off the pressure plate on the altar during the fight it must be lifted back onto the plinth and removed once more, or you can "walk" onto it and off by getting on the altar). Go back and talk to Ralis. He'll then ask for 2000 gold to hire some more miners.

Second Visit
Several days afterward you'll get another note asking you to come back to the barrow. There are more draugr and two of the miners are missing. He asks that you locate the missing miners and to kill the remaining draugr. In the last section of the mine near the corpse of Mireli is a handle (near the floor on the other side of the wall with candles, a soul gem and coins) that can be turned to reveal a secret room where Ahzidal's Ring of Necromancy can be found. Ralis now wants 3000 gold to hire some mercenaries.

Third Visit
You will receive a third letter a few days later, asking you to return to the barrow. When the courier delivers the letter, he will tell you ''"Another letter from Ralis. He's starting to scare me a little"'', a portent of things to come. Ralis will tell a similar story as last time: that there are yet more draugr, and that this time they have killed all the mercenaries that he hired. Enter the barrow and kill the draugr. To access Ahzidal's Gauntlets of Warding, pull the chain to the right of the iron doors that lead to the staircase into the newly excavated section, then backtrack around the corner where they will be sitting on a pedestal that was previously unavailable. Then, head down the stairs, avoiding the trap, and kill the new draugr. When you reach the open chamber, you must ensure all the pressure plates are lit for the gate to open and reach Ahzidal's Ring of Arcana. (The Light Foot perk does not prevent you from lighting the pressure plates.) The timing is a bit tight; if you can't get it, using Slow Time seems to work, or you can run along the joint between two rows of tiles, depressing both rows at once, for a total of three runs across the grid. You can also circumvent the puzzle entirely with Telekinesis. A pit filled with deep water surrounds the plinth that the ring is on. At the bottom you can find a coin purse, a burial urn and a leveled battleaxe. Once you're done here, head up the stairs and back out of the barrow to talk to Ralis who now wants 5000 more gold. He will then send you one last note.

A Poor Investment
When you get the final note, return to the barrow and look for clues at the camp, then head into the barrow and clear it out. You are finally able to reach the word wall which teaches a word for the Cyclone shout. On reaching the room with all the pressure plates on the floor, follow the passage to the left. A gate will close behind you will have to fight three draugr.  The gate blocking access to Ahzidal's Armor of Retribution can be opened by rotating the two animal totem pillars until the whale symbols are facing you, then pulling the lever on the floor.  Rotate the two animal totem pillars until the eagle symbols are facing you and pull the lever on the floor again to open the gate you came in, and the gate over the spiral staircase. At the bottom of the staircase, the gate blocking access to Ahzidal's Helm of Vision can be opened by rotating the two animal totem pillars until the snake symbols are facing you, then pulling the chain next to the door. Pulling the chain with an incorrect pillar arrangement will cause several flame spout traps to blast the area in front of the gate. Removing the helm from its pedestal will activate another flame spout trap that is aimed back towards the gate. Alternatively, you may use Telekinesis again. There is a Stalhrim source to the left of the helm chamber.

After battling several leveled draugr, you will eventually find Ralis completing the ritual to awaken a dragon priest named Ahzidal. Defeat Ahzidal, loot his eponymous mask, then speak to Ralis, who will explain that he was under a spell. You can then choose to kill him or let him live, in which case he will become available as a follower. If you kill him, you may loot Hoarfrost, a unique ancient Nordic pickaxe, from his corpse. You can also take it from him if you spare him.

You can find the Black Book Filament and Filigree at the end of the exit tunnel.

Notes 
In total you will require 11,000 gold to complete the excavation.
The time between each investment and the next courier message is three full days (72 hours).
If you visit between messages, there will be miners and possibly guards working. They have generic dialogue reflecting the current state of the quest.
Throughout the quest, a series of journals can be found, giving insight into Ralis' state of mind. Take care when reading them as the disappearance of the camp after defeating Ahzidal and dealing with Ralis will not occur if you take his journals from the camp prior to the final encounter. They may also be stuck in your inventory permanently if you do so.
You can find Ahzidal's unique heavy armor set and rings:
Ahzidal's Boots of Waterwalking are available after the first phase of digging.
Ahzidal's Ring of Necromancy may be found after the second phase.
Ahzidal's Gauntlets of Warding and Ahzidal's Ring of Arcana can be acquired after the third phase.
Ahzidal's Armor of Retribution and Ahzidal's Helm of Vision become available after the fourth phase.
You may hear the chanting of the nearby Word Wall after the second phase has occurred, but you won't be able to access it until the fourth phase. You might be able to access it during the third phase if you stand close enough to the wall.
The grate that opens to allow you to descend to meet Ahzidal on your final visit is controlled by the familiar pillars and is well-marked. The eagles on the opposite wall must be set on the corresponding pillars.
The iron gate blocking the pedestal that holds Ahzidal's Armor of Retribution is not so obvious, however. As you enter the room, on the walls to either side there will be pull chains just to the right of an arch-way. If you pull the chains, this will activate rotating doors which will reveal that behind the arch-ways are two more pillars, each with the sign of the fish. The pillars behind the chairs need to be matched to these to open the gate and obtain the armor. Setting both pillars to the Snake (and activating the lever) will unleash a trap of poison darts. The pillars here perform an uncharacteristic double-duty by opening two separate portals.
The mining camp outside the barrow will remain until Filament and Filigree is read or you leave the area after dealing with Ralis, at which point all traces of the camp will disappear, including Ralis's journals.
The fastest way to complete this quest would be to murder a Redoran guard, and serve the jail time rather than pay a bounty. This will cause seven in game days to pass each time, allowing quick completion.

Bugs
 
Check the site once, talking to Ralis, then sleep in a bed in Solstheim for 24 or 48 hours. Repeat for each stage.
 
 
 
  They may be removed via the console by typing   and repeating for the IDs xx01810F, xx018110, xx018111, and xx0181CB. The xx on each ID will vary; see this page for details.
 
Leaving and reentering Kolbjorn should fix this issue.
 
 

Quest Stages