Online:The Mallari-Mora

Quick Walkthrough
# Talk to Telenger at the Ezduiin camp.
# Find his student, Andewen.
# Collect the two runes.
# Search the Ezduiin Undercroft with Andewen for the missing researchers.
# Talk to Meldil. 
# Release or kill four assistants.
# Talk to Andewen, who tells you to kill Uricantar.
# Enter the Inner Sanctum
# Talk to Uricantar's projection
# Find Uricantar. 
# Kill him and recover the Mallari-Mora.
# Return to Telenger to receive your reward.

Detailed Walkthrough
 
Finding Telenger and his assistants
Talking to either Parmtilir, Rellus, or Umbarile will send you to Telenger the Artificer. Either speak with one of them or go to Telenger directly to begin the quest. Telenger will assume you came with supplies but will be hardly surprised this is not the case as his expedition to the ruin of Ezduiin hasn't been going as well as hoped. Telenger will name issues with spirits, supplies, and missing people. More precisely Andewen and her team, which he asks you to find. Asking a bit further for info, he will reveal he came to find the Mallari-Mori, an ancient talisman that took the lives of everyone in Ezduiin cursing their souls. He will also explain, however, that the undead in the area are new, and he believes that someone rediscovering the Mora is the cause. Further, he will mention Andewen being his most priced student here to assist him. When pushed about other people, he will mention Sirinque, with who he seems far less impressed. Talking to her will start the quest An Act of Kindness, which can be done in between to make the spirits that wander the area non-aggressive.

Go talk to Andewen, a bit further down the path from Telenger. She's within a magically walled place. She tells you she needs more runes. Go around the area to pick them up, then go to the Undercroft and speak there to Andewen. She will use them to unlock the door. Wait until she's done with that, then head inside. A bit further down you'll find Meldil, who till talk about trying to stop Uricantar and trying to help the other students, at which he failed, asking you to stop him yourself instead. He will also tell you he's using the others to keep a gate to a shard of Aetherius open. He will tell you that to close the gate you need to unbind the students or kill them, and that spirits named Thirsters are now inside the ruin. If you want, you can talk to Andewen before continuing, and she will tell you she used to be close to Uricantar until Telenger cast him out of the guild and forbade him from using magic. He did this because Uricantar didn't care for boundaries and would do horrible things to get power.

Deal with the bound students
Continue down the place avoiding the blue circles around the Thirsters. Note that the Thirsters won't attack you. Go to each student, and either use to amulet to enter the spirit realm then go to the binding stone to destroy it. If you go inside the spirit realm, be it by coming too near a Thirster or by trying to free a student, there will be Baleful Ghost who are aggressive. Unlike after getting near a Thirster, however, you will be transported back to the world of the living after destroying the binding stone. Each student will also give you a temporary protection spell after saving them that allows you to go near the Thirsters without consequences. After you either saved or killed each student, return to Andewen who relocated a bit further down the ruin for safety. The saved students will also be here.

Kill Uricantar
Now that everyone is either dead or back to safety, it's time to deal with the bad guy causing these problems. Go to the gate where you previously found Meldil. There, you will find a projection of Uricantar. Talk to it, and you find out that Uricantar seems to think Telengers issue is more against not wanting him to be successful rather than not accepting his rather hurtful to other methods, showing Uricantar indeed isn't very sane anymore due to his search for power no matter the cost. He'll also mention that he wanted to perform the life-binding with Andewen, revealing that them "being close" was more than friendship, although it's unknown if his feelings were returned. After this, enter the inner-sanctum. Inside you will find him and an altmer named Thundermaul. After you killed them both, return to Telenger. Hand him over the Mallari-Mora to finish the quest.

Notes
If you touch the aura of a Thirster while inside the Edzuiin ruins, you will be transported to the Spirit Realm and must head back to starting area to get out.
After you've defeated Uricantar, the quest marker will lead you back the way you came. You can ignore the marker and head to the entrance and avoid running through the dungeon and thirsters again.

 

Quest Stages