Darkness Returns

Objectives

 * Enter the Twilight Sepulcher
 * Speak to the Nightingale Sentinel
 * Follow the Pilgrim's Path
 * (Optional) Retrieve Nystrom's Journal
 * Return the Skeleton Key to Ebonmere
 * Listen to Nocturnal
 * Speak to Karliah
 * Choose Nightingale Role

Walkthrough
To complete this quest, the player must take the Pilgrim's Path to the Twilight Sepulcher in order to put the Skeleton Key back where it belongs. As you enter the Sepulcher, you stumble upon the ghost of Gallus Desidenius, the Nightingale murdered by Mercer Frey. He warns the Dragonborn that, because the Key is missing, the other ghosts have been corrupted and are now hostile. When asked about the trials ahead of you in order to reach the Ebonmere Lock, he advises you to look for a journal that belonged to another adventurer, Nystrom. His skeleton is to the left of Gallus.

Nystrom's journal holds some clues to the trials:

"Shadows of their former selves, sentinels of the dark. They wander ever more and deal swift death to defilers

"Above all they stand, vigilance everlasting. Beholden the murk yet contentious of the glow."

"Offer what She desires most, but reject the material. For her greatest want is that which cannot be seen, felt or carried."

"Direct and yet indirect. The path to salvation a route of cunning with fortune betraying the foolish."

"The journey is complete, the Empress's embrace awaits the fallen. Hesitate not if you wish to gift her your eternal devotion."

Nystrom also says that the man who gave him the clues "mumbled nonsensical phrases like "night is the new day" and how he was the "ghost of the sun"."

First Trial - Sentinels
For the first trial, you face the shadows of their former selves, sentinels of the dark - Nightingale ghosts, hostile and powerful. You can either sneak past or kill them. If you decide to kill them, there is valuable loot on both sides of this area.

When entering the first trials room, it is relatively easy to sneak attack the Nightingale sentinel with a bow and arrows directly infront of the player when entering. Then the player can easily continue on to the next trial or in the chance of receiving more loot, kill the other sentinels.

Be sure to look behind the desk in the room to the left. There is a button that lowers a stone wall. In the small room, you will find loot. The room also contains an alchemy table.



Second Trial - Light vs. Dark
"Above all they stand, vigilance everlasting. Beholden the murk yet contentious of the glow."

For the second trial, night is the new day: avoid the light and stay on the darkest path. Sprinting and using Whirlwind shout will make it easier. Watch for trip wires when travelling up the staircases. During this trial there are no enemies. Using healing spells will also help as you will not die as quickly. Also have healing potions as healing spells might not be fast enough. Candlelight and Magelight spells can also help if you have trouble finding your way around, as their own lights aren't harmful in this area (provided you can remember which areas "count" as dark).



Third Trial - Hidden Door
For the third trial, in the room with the statue and a dead bandit lying in front of it, there are two large sconces to either side of the statue. To the left of the left hand sconce there is a chain, and at the right hand side of the right sconce there is a second chain. Pull the two chains to put out the lights of the sconces, so giving her (Nocturnal) what she most desires (darkness). The door behind the statue will then open.

Fourth Trial - Sentinels vs. Traps
For the fourth trial, you have some options:


 * Straight ahead through the traps: watch your step and use Whirlwind Sprint or Become Ethereal. Be careful with the doors. The swinging axes can inflict diseases upon you, even if you are a werewolf or vampire.


 * Before you find the first trap, there is a Master locked iron door to your left that can be used to avoid the traps (you should have the skeleton key to easily open it). Sneak past the two sentinels.


 * As above, but kill the sentinels and loot the pit. Among other things it contains 2 skill books: Proper Lock Design and Sacred Witness).

Fifth Trial - Inner Sanctum

 * Note: After completion, the entire area will be sealed. If you want to collect the considerable valuable loot, you must kill all of the sentinels (except for Gallus) and search the area. If you are not strong enough to do that, consider leaving and delaying completion till later in the game.

Enter the Twilight Sepulcher Inner Sanctum, fall into the pit and search Anders' skeleton; read the message. Wait a few seconds until the Skeleton Key reacts. The ground will disappear and you will return the Skeleton Key to the Ebonmere Lock. You will summon Nocturnal, who will bid you to drink from the Ebonmere, "for this is where the Agent of Nocturnal is born".

You must then speak to Karliah, and she explains to you the choice you must make between the Agent of Strife, Subterfuge and Stealth. To pick one, you must simply step on the corresponding moon. They give you greater Powers, usable once a day only. The Dragonborn can choose to change the chosen power after a day so there is little pressure in choosing the "best" ability. After you speak to Karliah, Gallus' ghost will appear and they will speak shortly before he goes to the Evergloam. Karliah, then, goes back to Nightingale Hall. The Dragonborn can then leave through a portal.

Powers
Shadowcloak of Shadows
 * The crescent moon represents this power, which makes the player the master of remaining unseen. Once a day you can become invisible while crouching for 120 seconds, much like the Shadow Stone.

Nightingale Subterfuge
 * The half moon represents this power, which allows the player to utilize shadow to cloud the judgment of those around them. Once a day, you can activate it for 30 seconds in order to make people and creatures on the spell's area of effect attack anyone nearby.

Nightingale Strife
 * The full moon represents this power, which, when used, instantly absorbs 100 Health points from the target. This power can also be used once a day. Will go through the target and hit others.

Bugs

 * Nystrom's Journal may not appear in your inventory after speaking with Gallus.
 * There is a bug that can occur after Nocturnal is done speaking. The quest marker will follow her into the Ebonmere instead of moving to Karliah, so that you can't speak to her and are trapped in the room. Re-loading from before returning the key to the Ebonmere can fix this.
 * If you have the second "Hard answers" (glitch when you complete the Arch-mage line) leaving the last objective "speak to Karliah" incomplete you may complete it after Nocturnal's dialogue for a second "Nightgale Blade" reward for a duplicate item. It seems as though when the reward given is pro-rated according to your current level. ( the earlier blade will be weaker than the second blade if you progressed significantly between the two - example nightingale blade #1 (original) 43dmg absorb 15 health / 15 stamina, nightingale blade #2 (duplicate from bug) 50dmg absorb 25 health / 25 stamina) which ended up being better than an ebony sword - I waited quite a while before completing the quest so I could use the skeleton key everywhere - the damage quoted includes perk modifiers. http://i39.tinypic.com/birxg1.jpg
 * There is a bug that can cause this quest to be removed for your quest menu. Simply enter the Twilight Sepulcher to continue the quest.


 * Occasionally, the book Sacred Witness will not appear on the table it was supposed to.