Daggerfall:Nocturnal's Quest

Quick Walkthrough
# Summon Nocturnal on the 8  of Hearth Fire. (see Bugs)
# Head to the dungeon named by Nocturnal.
# Find and kill a mage.
# (Optional) Embark on a quest for another artifact.
# Travel to the town named by Nocturnal.
# Meet her worshipper there within the time limit and receive the Skeleton's Key.

Detailed Walkthrough
The Mistress of the Night
Nocturnal starts whispering to the player:

:''"You wish, (player's name), for power. With it you can thrash at shadows and have a hope. If I brought you this hope, what would you bring me? Would you destroy one who brings me pain?"

Accept
Nocturnal goes on:

:"Would you? You would be my anesthesia? You will go to the lair of the Mage (mage's name) at (dungeon) and slay (him/her)? Ah, (player's first name), for that I would give to you my Skeleton's Key which I have entrusted to my slave (worshipper's name). After (mage's name) lies dead, go to (town) and meet my slave at (building). You will recognize (him/her) easily - a (worshipper's description). There you will receive the Skeleton's Key. And now, I must return to my cold palace of Oblivion. I will await news."

Decline
Nocturnal answers sadly:

:"As I thought, no heart at all. We shall have no contract then, you and I, and, disappointed, return I to my cold palace. The souls within are no kinder than those here, but there, they follow."''

The Skeleton's Key
thumb|right|The mage would rather strike a bargain
Travel to the dungeon named by the Daedra Prince and find the mage within. There may be multiple mages inside the dungeon, but you must slay the specified target for the quest to count as a success. When hit for the first time, the mage will offer you a deal:

:''"Wait! I know that Nocturnal has sent you, and that she has promised you the Skeleton's Key. But if it is truly power you seek, I can top her offer -- if you cease your attack, I will tell you where to find (artifact). Do you agree to my offer?"''

The artifact in question will be Auriel's Bow, unless you already have that artifact in your inventory. If you do, the mage instead offers the Warlock's Ring (though this does not work as intended; see bugs). 

Accept the Offer
The mage continues:

:''"Excellent. I knew you had a mercenary's heart. (Artifact) lies hidden in (artifact dungeon). You have only to find it and you will be a power to be reckoned with indeed. Now, I bid you good day, lest you decide to claim both (artifact) and the Skeleton's Key by killing me. A mercenary heart such as yours should not be trusted too far!"''

Accepting the offer means betraying Nocturnal; after about a day she will send her minions after you. In addition you will lose 20 reputation with the Daedra Prince.

Travel to this new dungeon and find the artifact within. It will look like some rusty dungeon equipment, so you may want to use Info Mode (by default, the F3-key) when you come across any such items. It will say "You see a Auriel's Bow" etc., if you have located the artifact. Pick it up and leave the dungeon.

Two to thirty in-game minutes after picking up the artifact, the following message appears:

:Mocking laughter echoes in your mind,
:''"You should have known better than to trust me, (player's name). Perhaps this shadow of power can satisfy your craving for a time, while you rage vainly against those who actually possess it. Me for example. I do hope sweet Nocturnal won't be too displeased with your treachery."
:(Artifact) crumbles to dust in your hand.

Thus, this option ends in failure; you receive no reward and are out the cost of summoning Nocturnal.

Decline the Offer
Kill the mage. When the spellcaster dies, a message appears:

:"You have slain (mage's name). Prince Nocturnal will now rest easier."''

Now that the mage is no more, head to the town where Nocturnal's loyal slave waits for you. Ask around to locate the correct building and enter it. Speak to Nocturnal's worshipper for your reward.

Reward
thumb|right|Nocturnal's Worshipper
 
Speak to Nocturnal's worshipper and hear:

:''"So, you're (player's name), right? I'm (worshipper's name). I must say, I was wondering what kind of (player's race) it took to glide into a Mage's stronghold, murder the owner, and trip right on out. Very impressive. Nocturnal is likewise intrigued by you, hence this gift: Skeleton's Key. Be careful with it, (player's first name)."''

Reputation Gain/Loss
 

Additional Reputation
If you betrayed Nocturnal by accepting the mage's offer, you will lose 20 reputation with her.


Enemies
Random dungeon monsters
Quest Target: One Mage
4x One Frost Daedra every three in-game minutes (100% chance) if you betray Nocturnal
left
 

Notes
Although in-game sources say Nocturnal's summoning day is the 3  of Hearth Fire, it is actually the 8 .

Bugs
Nocturnal's Summoning Day is intended to be on the 3rd of Hearthfire (instead of the 8th). This is hinted at in the book Invocation of Azura, which is made less vague in the version found in future The Elder Scrolls games.
The Daggerfall Chronicles further supports the claim of her summoning day being on the 3rd.
The original quest is broken and will not work the way it was intended. However there is fixed version of this quest which offers also an alternate outcome along with a third possible artifact, the Staff of Magnus. This fix can be found here.
However this patch does not work the way it was intended by its creator and Auriel's Bow remains the one and only artifact you can get from the mage.
There is also a fix available for this issue; it can be found here.
You should be able to ask NPCs about Nocturnal, but her name may appear as a random name instead. The NPCs will still provide information on the Daedra Prince, however.

Additional Dialogue
If you ask an NPC about Nocturnal's worshipper, you may hear:
''"(Worshipper's name) is one of the regulars at (building), just (direction) of here."
"(Worshipper's name) is a (worshipper's description) who haunts (building). That's to the (direction)."
If you ask an NPC about Nocturnal, they may say:
"Nocturnal is the mysterious Lady of the Night, one of the Daedric Regents."
"Nocturnal is a Regent of Oblivion, whose sphere is darkness and mystery."''
If you ask an NPC about The Skeleton's Key, you may be told:
''"The Skeleton's Key can open any lock."
After you have accepted this quest, NPCs may say when asked for any news:
"(Mage's name) is a sneaky one -- (he/she) brings the whole Mages Guild under suspicion."
"I can't trust anyone at the Mages Guild, knowing (mage's name) is a member."
If you fail the quest, NPCs may say when asked for any news:
"I knew (mage's name) was in some kind of trouble, why else would (he/she) leave so quickly?
''"The Mages Guild must have decided (mage's name) was a liability to their image."
If you successfully complete the quest, NPCs may say when asked for any news:
"Well, I can't say I'm surprised about (mage's name); (his/her) past caught up to (him/her)."
"I don't even think the Archmagister is sad to hear of the death of (mage's name)."''

Quest Log