Detailed Walk-through courtesy of the UESP Wiki interspersed with my own screenshots from the game. Done because it does the quest justice to have such a detailed explanation rather than my summary.
Tharstan
The small settlement of Skaal Village are inhabited by Nords living life the old way, with their own culture and religion, especially the worship of the All-Maker. This welcoming and hospitable people let an elderly historian and author named Tharstan live in the village so he could study and document the ancient Skaal traditions. Using what he learned of Skaal culture, Tharstan wrote Children of the All-Maker, and the next book is nearly finished. He also married the Skaal leader Fanari Strong-Voice and now lives in the largest building in town, the Greathall. However, after your heroic rescue of Baldor Iron-Shaper during the quest A New Source of Stalhrim,
Tharstan will decide that you are the right person for a task he has in
mind, and will actively seek you out when you next visit the village.
As it turns out, Tharstan is not only interested in Skaal traditions,
but is equally interested in the many ancient ruins scattered all over Solstheim,
claiming to know most of them well enough to draw a detailed map from
memory. However, his recent discovery has left him quite nervous about
exploring by himself, so he wants you to accompany him as backup.
According to Tharstan, a new passage was unveiled during an earthquake
caused by the eruption of Red Mountain. The passage revealed the entrance to Vahlok's Tomb. When you agree to go with him, Tharstan will run off to his temporary home, the Greathall, to pack for the trip, hoping you will meet him there as soon as possible.
A Tomb Uncovered
Vahlok's Tomb is located south-southeast from Thirsk Mead Hall, directly east from Kagrumez.
Be sure to stock up on potions and have your best weapons on hand, then
take the trip to the tomb. You will find the entrance located at the
end of the passage caused by the earthquake. Head down the first tunnel
and you will find Tharstan waiting for you. His fascination with the
tomb is immediately apparent:
"Remarkable, isn't it? This tomb has been hidden for... well, who knows how long. Many centuries, I would think." He will then proceed to offer you the first task:
"There are some sealed doors up ahead. Perhaps you can figure out how to get them open." He will then guide you down a set of stairs and keep talking:
"I've had a look around and the only interesting thing I've found is this inscription here, and a switch below it." When he arrives at the inscription and the switch he will continue:
"Now,
I'm not sure if you can read the dragon language, but this seems to be a
riddle of some sort. "A sacrifice will bring you closer to that which
you seek." I wonder what it means."
When you examine the room it soon becomes clear what needs to be done: dead draugr
are scattered all around a gigantic burning hole in the floor, with
only a grate to keep you from falling down. As per Tharstan’s hint, drag
one of the draugr enemies onto the grate, then head back up on the
podium and activate the handle underneath the inscription. This causes
the grate to disappear and the draugr will fall into the flames, acting
as the sacrifice needed. While the draugr burns, two entrances in the
room will open, one to the north and one to the south.
Southern Gate
Head down the southern tunnel and open the iron door. This opens a
path through the catacombs, where four leveled draugr enemies will rise
and attack. If you are not carrying arrows, pick up a few from the
draugr archer in this area; you will need them to solve a puzzle later.
Head up the stairs to the east and activate the chain. When the door
opens, you and Tharstan will arrive in a puzzle room with three pillars
surrounding a large central pillar with different colored symbols.
Tharstan will immediately head up to a plaque and start reading:
"Hm...
three pillars. Other than that plaque, there doesn't seem to be
anything else worthy of note. Let's see what the inscription says. "All
men must die, often by their own means." Sounds rather grim, if you ask
me." He will then wander around the room, mumbling:
"They also
have glowing stones of some kind at the top. They look vaguely similar
to drawings I've seen of objects called Impact Stones."
To solve the puzzle, position yourself behind one of the three
pillars and different attacks, related to the weapons placed on
pedestals near the central pillar. Going clockwise from the plaque, use a
melee attack for pillar one, an archery attack for pillar two, and a
magic attack for pillar three. When all three pillars have been
activated, the door to the north will open and provide access to the
final chamber. Here, two draugr enemies will burst out of their
sarcophagi, along with a boss-leveled draugr. After the battle, Tharstan
will come rushing in and start to study the chamber, saying:
"These
runes have faded a bit, but I believe I can translate the inscription.
The writing describes a guardian who defeated someone named Miraak. In
fact, if I'm reading this correctly, it says that Miraak was a traitor.
Most interesting." Once he is done, he will start looking for an exit, so make sure you loot the boss for the left part of the Amethyst Claw and approach the word wall for a word for the dragon shout Battle Fury. When you are finished, locate the open sarcophagus and follow the narrow tunnels back to the central chamber.
Northern Gate
Head down the northern tunnel and unlock the minor loot chest in the
alcove for a bit of treasure. Tharstan suspects that this room contains
another puzzle: "I expect there's another riddle in here, along with a
puzzle. "Continue along the path, don't tread where you've been.."
Interesting..." He will then look at the odd stone path in the center of the room and conclude: "Well,
I'm pretty sure about two things. One, the riddle is most likely
referring to these flat square stones. And two, I'm not going anywhere
near them." With these words, he will find a safe spot and let you
handle the rest. The puzzle is quite simple: just go from one square
stone to the next, without ever touching one of them twice. Once all
nine squares have been pressed down, the way to the final room will
open. In there, four draugr enemies and a boss-leveled draugr will
immediately attack you while Tharstan runs to safety.
After the battle, the old scholar will return to the room and start his studies, saying
"Look!
Here's another wall with dragon language inscriptions on it! Let's find
out what's written here. This writing refers to a guardian who inspired
both men and dragons. I wonder if the guardian was himself a man or a
dragon?" Loot the boss for the right half of the Amethyst Claw
and approach the word wall for a word for the dragon shout Battle Fury.
Lastly, locate the open sarcophagus to the south and follow the narrow
tunnels to a chain that, when activated, lowers a stone wall and
provides a very quick shortcut back to the central chamber.
The Amethyst Claw
With the two parts of the Amethyst Claw in hand, it is time to unlock
the odd cage in the central chamber. Insert the corresponding claws in
the keyholes on each side of the stairs leading to the cage. When the
cage opens, your elderly sidekick will jump into the cage and translate
the plaque:
"Here's another riddle. "Stay your course. To idle is to
die." Well, at least it's straightforward. There appears to be a switch
of some kind here. I'll just stand over here while you flip that switch.
I'm sure everything will be fine." Flip the switch, and several
magical platforms will start to emerge and disappear all over the watery
area in the chamber, leading to an entrance for away. You will have to
follow the platforms while they are present and be on the next platform
before the former disappears. When you make it to the other side, the
magical platforms will turn into a bridge and Tharstan will be able to
join you.
A Bridge Too Far
Head through the corridor and face the next challenge: a gigantic chamber overflown with water and several corrupted shades
lurking below. The drop is a very long one, but luckily a handle is
present to create more magical bridges. Activate the handle and follow
the bridge as it appears and disappears, landing you on a small alcove.
Once again, the platforms will become permanent once you traversed them
once, so Tharstan will soon follow, commenting everything. Yet another
magical bridge awaits, and its platforms disappear even faster than
before. The last bridge leads to a huge iron door to the north. If you
fall down you will not only suffer damage from the fall, but will have
to deal with the corrupted shades and locate one of the various
shortcuts back to the bridges above.
After the last bridge, Tharstan will open the gate leading to the ruins’ Hall of Stories, excited as always:
"Ah,
the Hall of Stories. These are found in many ancient Nord tombs. There
must be hundreds of years of history etched in these walls. Too bad they
seem to be too damaged to read." He will then consider the dragon claw puzzle door:
"Hmm...looks like it needs some sort of key. Maybe those half claws you found would fit in here if you put them together?"
Naturally, he is correct, but the right combination is nowhere to be
seen on the claw, so you will have to pay attention to Tharstan as he
deciphers the writings on the walls:
"Perhaps there's enough
undamaged text in these etchings to tell us the combination. Ah, yes,
here's something. The first one has to do with a breeze, or maybe it's
wind. The second one mentions the the [sic] night sky, and the moon. And the third has something to do with fire. It also seems to mention scales." He will then ask you to figure out the combination from these small tips. Turn the rings on the door to
Eagle-Wolf-Dragon and insert the Amethyst Claw in the keyhole.
Vahlok the Jailor
The puzzle door will lower to reveal a long staircase leading up to a
chain that opens the way to the final chamber. The chamber itself is
essentially one big trap, as almost all the tiles on the floor are flame spout traps.
Before entering, make sure to down a potion that protects against fire
damage and equip apparel that increases your fire resistance. You will
not make it far into the room before the legendary dragon priest Vahlok the Jailor
bursts out of his sarcophagus and starts to throw high-level fire
spells at you, so do your best to fight him and avoid the fire.
After the battle, old Tharstan will once again come out of hiding and start studying the word wall:
"Hmm,
here's another mention of the guardian. I can only assume that this is
the guardian's tomb we are standing in now. It says that he was loyal,
and his reward was an honorable death. Quite fascinating." Tharstan
will reward you with 1000 gold and tell you that he will stay in the
tomb a while longer, for further studying. Before leaving, make sure to
loot the remains of Vahlok for a hefty amount of gold and search his
boss-leveled chest. Learn the third and final word for the Battle Fury
shout, then backtrack all the way to the entrance.