Oblivion:Namira

Quick Walkthrough
# Once you have reached level 5, travel to the Shrine of Namira and talk to Hjolfrodi. You are deemed too attractive to worship Namira, so lower your personality to 20 or below.
# Once you are unattractive, speak with Hjolfrodi again and activate the shrine.
# You are next tasked with eliminating the priests in the Anga ruin. You are given a special spell, ''Namira's Shroud to deal with them.
# Travel to the Ayleid Ruin, Anga, and cast Namira's Shroud'' on the priests.
# Return to the shrine to be rewarded with the Ring of Namira.

Detailed Walkthrough
Locating the Shrine of Namira
Namira's Shrine is east-southeast of Bruma, and northeast of where the Silver Road and the Orange Road meet.  Unlike several other Shrines, nobody can point out its location.
An Offering to the God
Once there, talk to Hjolfrodi the Harrier and to learn that you are too attractive to worship Namira. You just need to lower your Personality to 20 or lower. As long as your Personality is at most 60 (or 100), you can do this by drinking cheap wine (one effect of which is to drain Personality 10 points for 2 minutes), available in any town or city.  Since at most four potions can be drunk at once (or eight using an in-game exploit by exiting the menu, then entering and drinking 4 more), cheap wine will not be powerful enough if your Personality is greater than 60 (or 100); in that case, you will need to take more drastic steps, as detailed in the next section. Once back at the shrine, drink the wine and make sure your Personality is at or below 20. Quickly talk to Hjolfrodi and then quickly activate the shrine (both steps require low Personality).
:You dare approach my shrine, Child of the Light? You, who walk this plane basking in the light of the warm, cruel sun? Prove to me that you deserve my favor. In Anga, my Forgotten have lived in peace for many years. They worship me from the dark, basking in their misery and filth. Now, though, some would seek to bring light to their darkness. Priests of Arkay have intruded upon their squalor. I want you to help my Forgotten kill these priests of the Light. Cast this spell upon the priests. Allow my beloved Forgotten to kill the interlopers. When this is done, I shall reward you for your efforts.
Reducing your Personality
Drinking cheap wine is definitely the easiest way to reduce your personality. Most chapels contain an abundance of cheap wine in their basements that is unowned and can be taken without penalty. If you need to reduce your personality by more than 40 (or 80) points, however, there are some options (all of which can be done in conjunction with drinking cheap wine): 
You can buy one of several unique items available in stores:
Helm of Ferocity is a helmet that has a constant-effect Drain Personality of 5 pts.
Document of Purile Banter  is a scroll that provides, among other effects, a Drain Personality of 50 pts for 150 secs.
Chronicle of Sacrifice is a scroll that provides a Drain Personality of 50 pts for 30 secs, although be sure not to cast it at one of the priestesses.
When using either of these scrolls, be sure you have nothing equipped that resists magic as this will weaken the drain effect.
A custom Drain Personality on self spell can be made, although gaining access to this effect is difficult, as explained in more detail in the Drain Attribute article.
If you have completed the Repairing the Orrery DLC quest, you can use the Orrery power ''Secunda's Opportunity'' (when available) to lower your personality by an additional 20 pts.
The Scales of Pitiless Justice obtained from the Dark Brotherhood questline lowers personality when in your inventory, but it is only by two points, so it doesn't help much.
If you are at least a Journeyman Alchemist, you can make a potion of Restore Fatigue with the side effect Damage Personality; an easily available set of ingredients are Flour and Leeks. Since this potion damages (as opposed to draining) personality, repeated consumption by itself can be used to reduce personality to any level. Visiting a shrine or making a potion of Restore Personality afterwards will be needed to restore your personality.

The Task at Hand
It's now time to carry out the task that Namira has set for you.  Head to the Ayleid ruin Anga to the south of the shrine.

Namira gave you the spell ''Namira's Shroud, which is a Novice-level alteration spell with a base cost of 50 Magicka.  Most characters should be able to cast it, although characters with low Alteration skill levels will have a higher Magicka cost (see Spell List Notes) and may need fortified magicka. To complete the quest, you need to cast Namira's Shroud'' on each of the priests in the ruins. The Forgotten will then kill them. Do not attack the priests yourself or you will not get the reward. When all four priests are dead, you'll get a journal entry.

The main quest will take you to Cheydinhal before you are asked for a Daedric artifact. This gives you a chance to do the A Brush with Death quest and receive the Apron of Adroitness, which has enough fortify intelligence to enable low intelligence characters to cast the spell.

Returning to the Shrine
Return to the shrine to receive the Ring of Namira, a ring with powerful Reflect Damage and Reflect Spell enchantments.
:''You have cleansed my followers' perfect darkness. The Forgotten are free to wallow in their misery. Take my ring. Let it bring pain to others who would wish it upon you. Namira blesses you.

Notes
It is recommended to do this quest before your Personality reaches 60 (or 100), as after that it becomes much more challenging to drop the attribute to the amount required to start the quest.
Another option is to Damage your Personality rather than drain it. This can be accomplished with several alchemical effects: for details see the  .
Quest completion only requires that the priests die but not at your hands. This can also be accomplished by releasing the undead near the end of the dungeon and leading them back to the priests. 
The Namira's Shroud'' spell changes the torch carried by the targeted priest of Arkay from a standard torch to a special type of torch that cannot be lit.  After the priests have died, you can retrieve these torches.  They will be listed separately in your inventory from other torches.  If you equip one of them, the torch will go out immediately. This spell has no effect if cast on other torch carrying NPCs, it only affects Priests of Arkay.

Bugs
 
If you've failed Namira's quest and thus been disqualified from ever getting Hermaeus Mora's, all hope is not lost. See Mephala quest bugs for a workaround.
 

Journal Entries