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.''

Overview
It is obtained in a random encounter with one of the Afflicted or by approaching Kesh at the Shrine to Peryite. The Dragonborn must be level 10 or above to get the quest from the Afflicted, and level 12 to get the quest from Kesh.

Kesh tells the Dragonborn that in order to speak to Peryite, they must: After doing so, Peryite will appear to the Dragonborn and entreat their aid in cleansing the Afflicted, who are being led by Peryite's current champion Orchendor. Orchendor has "strayed from the path," displeasing Peryite, who will command the Dragonborn to:
 * 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.

Initial items
Collecting the flawless ruby is by far the hardest part of the initial task. There are a few methods to be tried in order to get one for this quest:
 * Upon entering either the Hall of Countenance or the Hall of Attainment on the left and right side of the courtyard of the College of Winterhold, a ruby can be found on one of the shelves in the rooms.
 * In Mistveil Keep in Riften, the Dragonborn can talk to Harrald, who will ask the Dragonborn to retrieve his sword from Balimund. Once complete, saving the game is suggested just before speaking with him again. He will provide a random gem combination as a reward. If a flawless ruby is not part of that collection, reloading from the save and repeating the process will eventually result in a ruby.
 * A flawless ruby, along with other precious gems, can be found in a broken boat in the river southwest of Sky Haven Temple and northeast from the Markarth Stables. 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. Saving before find the boat is recommended. (An Abandoned Rowboat, unmarked location)
 * Mining various ore veins may produce a flawless ruby.
 * They can be found when looting dead dragons.
 * Up to three can be found at Avanchnzel during the quest "Unfathomable Depths." A higher character level (level 31) is required.
 * In Shriekwind Bastion, the quickest way is to enter through the south entrance and keep taking left paths until a single throne in a blood-splattered room is reached. The floor near the unlit fire pit on the right should be examined closely for the ruby. Note that the ruby is not necessarily flawless.
 * Near Reachwater Rock, the stream that exits the cave should be followed, and eventually a rowboat will be encountered. In that boat, amongst other things, is a ruby. Note that it is not necessarily flawless.
 * The Prowler's Profit perk makes obtaining flawless gems of every type easy.
 * During the quest "Hail Sithis!," on the Katariah, one can be found in the Emperor's room, on the table in front of his bed.
 * In the Thieves Guild, some fishing jobs from Delvin, or shill jobs from Vex, will yield one.
 * Hidden chests in Dawnstar, Whiterun, and Windhelm may contain one, if the Dragonborn is at a high enough level.
 * The Thieves Guild tribute chest may contain one.
 * Mjoll the Lioness may have one for trade.
 * In the Arch-Mage's room at the College of Winterhold, one is in the safe.
 * Depending on the Dragonborn's level, giants may rarely drop flawless gems.
 * A gem can be found on Mercer Frey during the mission "Blindsighted."
 * Most higher-level vampires will have a gem of some kind in their inventory.
 * If is installed, then a flawless ruby can be found just to the left of the Inner Sanctum in the Forgotten Vale, on a skeleton. This requires careful handling as the skeleton is located very close to the edge and they will fall off and into the valley if the wrong gem is picked up first.

Deathbell can be found at the Alchemist's Shack, near Ivarstead, throughout the swamps of Hjaalmarch, and on the west coast of Solstheim. It can be found at Anise's Cabin, in the beginning of the game. It can also be bought at an alchemy store, which can be found in any city.

Silver Ingots and Vampire Dust can be easily obtained during the Companions questline because members of the Silver Hand often carry these. If embarking upon an entire quest line to get these items is a problem, they can be purchased in shops throughout Skyrim, along with the Deathbell. There is also a Silver Ore Vein on the western base of the shrine's mountain (although a smelter will need to be found to convert the ore to an ingot). There are Silver Ore mines and a smelter in Karthwasten to the southeast of the shrine.

Speaking to Peryite
Once all necessary ingredients have been gathered, they should be brought back to Kesh at the Shrine. Upon inhaling the fumes, Peryite will begin a conversation with the Dragonborn. He will give a task to kill his current overseer, Orchendor, who has forgotten his duty to Peryite. He will also state that the Dragonborn will replace Orchendor as his new champion.

Kill Orchendor
Orchendor is a mage (fire/ice) who resides in the Dwemer underground fortress called Bthardamz. It will be quite a challenge to find him there, because Bthardamz consists of several levels and areas filled with Afflicted (minions of Peryite that Orchendor guides) and Dwemer Automatons. The article on Bthardamz provides a good guide to navigating the dungeon.

On the way to Orchendor, the Dragonborn 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. They can either be fought or sneaked past, depending upon the Dragonborn's 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 for being able to continue attacking him as he teleports.

Alternatively, one with the Assassin's Blade perk, a decent dagger, an invisibility potion/spell and possibly the Shrouded Gloves should be able to kill him with a successful sneak attack.

Once he is defeated, his valuables and loot should be taken, including the key to the Bthardamz Elevator. Exiting using the elevator will avoid retracing the long journey through Bthardamz.

Upon return, Peryite will reward the Dragonborn with the Spellbreaker.

Trivia

 * After completing this quest, Afflicted Remnants may be found wandering Skyrim.
 * The "incense" that the Dragonborn inhales to speak to Peryite is identical in appearance to the vats of "ichor" in Bthardamz and the spew that the Afflicted use against the Dragonborn.
 * The colors of the world are much more vibrant when speaking to Peryite than they are before and afterwards. There is also a slight blurring when under the effects of the "incense."

Bugs
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