Black Book: The Sallow Regent (Quest)

Walkthrough
Read the Black Book found in the White Ridge Barrow.

Travel through Apocrypha; this is not as easy as it might seem, as the darkness of the realm is harmful and drains health without a light source of some sort, be it a spell or a torch. There are moving light sources throughout that act as safe havens.

In the first room, there is a pod just past the small pool with a tentacle on the right side. Wait for a moving light and follow it  safely down the hallway to the next room. There will be another pod just outside the lit area on the left hand side of this room. Follow another light through the next hallway.

After following the second hallway, there is a large open area with stationary lights near the entrance and exit. A large beam of light will periodically travel from left to right. Inside there will be two Seekers. On the left right next to the entrance is a pod, and on the right side of the room there are several books, soul gems, and scrolls. There are also some soul gems on a table toward the far end of the room on the right. All of the loot is hidden by darkness, so using a light source such as a torch or spell is recommended to find it.

Follow a moving light down the hall to the next area. This space has a series of bridges, some of which will retract and extend. There are also several Lurkers in this area(3-4 depending on level), which may stall the player and force them to fight in darkness. This area is also more difficult, as the moving lights do not follow the path the player must take directly. Using the spell Candlelight is very useful for this area. (Alternatively you can use one of the following: Stendarr's Aura, Magelight (though with some difficulty), or a Torch) After killing or avoiding the Lurkers there is a staircase; climb it to reach the final room, where there are two tables with books, scrolls, and soul gems, as well as a vessel with more loot. The Sallow Regent will be located on a pedastal at the center of the room.

Read The Sallow Regent.

At the end, the Dragonborn may choose one of these effects:
 * Seeker of Might - 10% more effective combat skills.
 * Seeker of Sorcery - 10% reduction in cost of all spells, 10% improved enchanting.
 * Seeker of Shadows - 10% more effective stealth abilities, 10% improved alchemy.

Only one of these effects can be active at one time. Read The Sallow Regent again to change to one of the other effects. (you will not have to redo the dungeon, as you will simply return at the end)

Trivia

 * Seeker of Might affects all skills in the Path of Might, including smithing, heavy armor and block.
 * Using the spell "Candlelight" seems to provide enough light to prevent the decreasing of health, so you don't need to follow the hovering lamps.
 * If you fall so far and one survives then a pop up comes up and says you can only fall so far. You will then revert to the top of the map and lay down and die.

Bugs
The second extending bridge cannot be crossed. Whirlwind sprint is also ineffective (there is an invisible barrier). This error must have been introduced in a recent update, as the above wiki seems to indicate that it is possible to complete this quest, which is no longer true. There is currently no known solution, and it is impossible to complete the Sallow Regent quest.

ru:Черная книга: Болезненный правитель (Квест)