Oblivion:Meridia

Quick Walkthrough
# Once you have reached level 10, find the Shrine of Meridia and make an offering of an ingredient from an undead creature to have Meridia speak to you.
# After the offering is made, Meridia will instruct you to wipe out the necromancers in Howling Cave.
# Once the necromancers are dealt with, return to the shrine to be rewarded with the Ring of Khajiiti.

Detailed Walkthrough
Locating the Shrine of Meridia
Chart a course west-northwest from Skingrad's west gate to find Meridia's Shrine between Cursed Mine and Shardrock farm. You must be at least level 10 to start. Talk to Basil Ernarde at the shrine to begin.

An Offering to the God
Meridia, Lady of Infinite Energies, is associated with the energies of living things, and has a particular dislike of undead creatures. Bring an ingredient from an undead creature (Mort Flesh, Ectoplasm or regular Bonemeal) to the shrine to talk to her. Once presented with the proper offering, Meridia will speak to the player:

:By the detritus of the profane, I am brought forth. And by your offering, you have made the profane your interest, mortal. The undead are foul, unnatural things. Some of my rivals take pleasure in these abominations. Not Meridia. I wish these creatures destroyed. Hidden behind a door, deep in Howling Cave, are necromancers. They rob graves for the materials to raise their undead armies. Find these necromancers. Destroy them and their abominations. Do this, and earn the gratitude of Meridia.

The Task at Hand
Go to Howling Cave, which is east of Castle Skingrad. The necromancers are located directly behind the door at the end of the northern passage, so only enter if prepared for a fight. The necromancers have several potions (due to a bug) and are aided by several leveled undead in addition to their own summoned creatures, all of which can quickly overwhelm you through their sheer numbers if you are not careful. It is recommended to kill the necromancers first to prevent them from summoning additional creatures. Use of enchanted weapons, fire damage poisons, and stealth may also be useful. Command humanoid spells are particularly useful for this quest, and provided you have a good sneak skill, you can avoid taking any damage using them.

Returning to the Shrine
Return to the shrine after all five necromancers are dead, and Meridia will applaud your actions: 
:Well done. Those creatures were an affront to all life, and they have paid the price for their actions. Take this ring and go with my blessing.

Meridia will reward you with the Ring of Khajiiti, a ring with Fortify Speed (+10) and Chameleon (35%) enchantments.

Notes
thumb|Location of ectoplasm
If you have already killed the Howling Cave necromancers before starting the quest, your journal will immediately update after Meridia gives you your task, allowing you to finish the quest without revisiting the cave.
The offering needed to activate this quest must specifically be either Ectoplasm, Mort Flesh, or regular Bonemeal. Meridia will not accept the rare 2-gold variety of Bonemeal (collected from Deranged Zombies), nor will she accept the remnants of Undead creatures that are found exclusively in the Shivering Isles: Bone Marrow, Bone Shard, and Hound Tooth.
There is a portion of ectoplasm on the ground just behind the benches at the shrine, in case you need some.  It is translucent and half-embedded in the ground, so you will likely have to rely on the hand icon to show you that you're looking at it.
If you are at a level where liches spawn, you may wish to try and draw them into range of the necromancers as they are not allied with them and will attack them.

 

Journal Entries