The Only Cure

Background
"A Khajiit named Kesh has offered to help me commune with Peryite. He asked me to acquire a deathbell flower, flawless ruby, silver ingot and some vampire dust."

- The Dragonborn Kesh the Clean at the Shrine of Peryite will trigger the quest.

Overview
Obtained in a random encounter with one of the afflicted or by approaching Kesh at the Shrine to Peryite (must be level 12 or above).

Given at the Shrine to Peryite by a Khajiit named Kesh the Clean. He tells the player to speak to Peryite, they must:
 * Obtain a Silver Ingot
 * Obtain a Deathbell flower
 * Obtain some Vampire Dust
 * Obtain a Flawless Ruby
 * Give all of the acquired items to Kesh
 * Inhale the fumes
 * Kill Orchendor
 * Report Orchendor's death to Peryite

The quest can also be triggered by just collecting the items needed (listed above) and going to the cauldron and activating it. This will start the quest.

Walkthrough
Collecting the ruby is by far the hardest part of the initial task. There are a few methods you can try in order to get one for this quest: The Silver Ingot and Vampire Dust can be easily obtained during the companion questline. The members of the The Silver Hand often carry these. If, however, you do not wish to embark upon an entire questline to get these items, they can, along with the deathbell, be purchased in shops throughout Skyrim.
 * Go to Mistveil Keep in Riften and talk to Harrald, who will ask you to retrieve his sword from Balimund. He will then reward you in a random gem combination. If you don't get the flawless ruby on your first try, just reload the most recent save and repeat the process.
 * A Flawless Ruby, along with other precious gems, can be found in a broken boat in the river southwest of Sky Haven Temple. They are sitting in the boat under the seat near the strongbox but not in it. There will be at least one flawless gem, but a flawless ruby is not guaranteed.
 * A Silver Ore Vein within the Sanuarach Mine. Remember to save your game, then mine all five veins at once. If you do not get a Flawless Ruby, reload your save and repeat until you get one.
 * Killing Dragons.
 * Up to 3 can be found at Avanchnzel during the Unfathomable Depths quest. A higher level (reportedly found at level 31) is required.
 * In Shriekwind Bastion. The quickest way is to enter through the south entrance and keep taking left paths until you reach a single throne in a blood-spattered room. Examine the floor near the unlit fire pit on the right for the ruby (ruby is not always flawless).
 * Near Reachwater Rock. Follow the stream that exits the cave, and you'll come across a rowboat. In that boat, amongst other things, is a flawless ruby.
 * The Prowler's Profit perk makes obtaining flawless gems of every type easy.
 * During the Hail Sithis! quest. On the Katariah you can obtain it in the Emperors room (in the same room as his bed) on the table just in front of his bed.
 * In the Thieves Guild, take a fishing job from Delvin, or a Shill job from Vex.
 * Hidden chests in Dawnstar, Whiterun, and Windhelm may contain one, if you are at a high enough level.
 * The Thieve's Guild tribute chest.
 * A trade with Mjoll the Lioness.
 * The arch-mage's room at the College of Winterhold, in the safe.
 * Rarely, dependenting on a player's level, Giants will drop flawless gems.
 * A gem can be found on Mercer Frey during the mission Blindsighted
 * In Movarth's Lair, when looting the master vampire.

Once all necessary ingredients have been gathered, return to the shrine and inhale the fumes. Peryite will enter conversation with the player. He will give you a task to kill his current overseer, Orchendor, who has forgotten his duty to Peryite. He will also state that you will replace Orchendor as his new champion. Orchendor is a mage (fire/ice) who resides in Dwemer underground fortress called Bthardamz. It will be quite a challenge to find him there, because Bthardamz consists of a few levels and areas filled with Afflicted (minions of Peryite that Orchendor guides) and Dwemer Automatons. However, the article on Bthardamz provides a good guide to navigating the dungeon.

On your way to Orchendor, you may find the Afflicted's Note, saying that Orchendor has gone down to the 'Aerdrome.' There is no place named Aerdrome in Bthardamz. Instead, what is meant is the Bthardamz Arcanex. At the Arcanex, Orchendor is guarded by numerous Dwemer Automatons, including a Dwarven Centurion. Fight them or sneak past them, depending upon your abilities. Orchendor is in the large room past the centurion. He deals considerable Destruction damage and is completely immune to fire, frost, and shock spells, as well as absorption effects. He is capable of teleporting and will often do so up to the upper tiers of the room. Physical weapons are recommended to slay him, and archery is useful to be able to continue attacking him as he teleports. Once he is defeated, gather his valuables and loot, including the key to the Bthardamz Elevator. Exit using the elevator to avoid to retrace your long journey through Bthardamz.

Return to Peryite, who will reward you with the Spellbreaker.

Bugs

 * If you manage to glitch through the door leading to the elevator to the Arcanex, and thereby killing Orchendor ahead of time, you will be unable to complete the quest.
 * The lever next to the iron bars may not appear. *Fix by fast traveling to a near city, then fast travel back.
 * After you give all the acquired items to Kesh, you can pick his pocket and get all the items back before he created the fumes. This doesn't interrupt the quest because he is still able to create the fumes (even without those ingredients), and the Dragonborn is still able to proceed with the quest.
 * The room before encounter with Bthardamz may have a bugged floor, in which the player falls to the door leading into the lower parts of the dungeon. Try using whirlwind shout to get to the other side.
 * Any follower can fall through, rendering them lost.
 * If the player talks to Kesh while he is creating the fumes, the quest will not be updated.This may cause the trophy/achievement "Oblivion Walker" unobtainable,since the player cannot obtain Spellbeaker.
 * Update: You can fix this by killing Kesh, taking the ingredients, and activating the cauldron yourself
 * The Spellbreaker is a shield and is most often added without the echo-text telling you it has been added to your inventory, even though it is. Check your inventory properly.
 * If you give the required items to Kesh while he is at the alchemy table, the quest sometimes does not update. Note, the cooking pot may also trigger this as I have given him the items and he walked to the cauldron but nothing occurred. I had to load a previous save and return to get him to work properly.
 * If you collect all items and do not have them in your inventory when you give to Kesh you cant proceed with the rest of the quest.
 * The Spellbreaker is simply not given after the quest is completed. Just clear the cache and load an earlier save.

Trivia

 * After completing this quest, Afflicted Remnants may be found wandering Skyrim.

Behind the scenes

 * Unless otherwise stated, the information above was obtained from in-game play or from The Elder Scrolls V: Skyrim Creation Kit.

Appearances

 * The Elder Scrolls V: Skyrim