Deathbell

Deathbell is a rather useful ingredient for the creation of poisons. Damage health poisons using Deathbell create stronger results than most other ingredients with the same effect. It also provides an excellent base for additional effects, such as the Weakness to Poison, which will amplify the effects of Damage Health.

Background
"Folklore abounds about this flower found in the swamps of Hjaalmarch. Some stories claim it grows where unfortunate deaths have taken place, others insist it grows first and then lures unsuspecting people and animals to their doom. I have found no direct evidence to support these stories; indeed I found the flowers difficult to locate at all. While it is most well-known for it's use in Poisons, it would be remiss to overlook that the blooms of the deathbell are very effective in mixtures for boosting ones Alchemy skill."

- Agneta Falia Herbalist's Guide to Skyrim

Quests
Ingun Black-Briar, an apprentice alchemist sends the Dragonborn on an errand to collect 20 Deathbell, 20 Nirnroot, and 20 Nightshade to help replenish her mentor's dwindling supply.

Kesh the Clean, a worshipper of Peryite, sends the Dragonborn on a quest to retrieve a Deathbell, some Vampire Dust, a Flawless Ruby, and a Silver Ingot so that he may commune with Peryite.

Locations

 * A couple can be found in the College of Winterhold on a shelf in the Hall of Attainment.
 * A concentration of Deathbell can be found around the Abandoned Shack, in the swamps east of Solitude docks.
 * Some Deathbell can be found within the Blue Palace.
 * Many (more than 20) Deathbell plants grow in and around the town of Morthal.
 * Growing in the swamp area surrounding The Apprentice Stone.
 * A few can be found just within the entrance of the Dawnstar Sanctuary.
 * Two Deathbell plants grow in the garden of the Alchemist's Shack.
 * Enthir at the College of Winterhold, sells 3 at a time which restocks every 2 days.
 * Babette, at the Falkreath Sanctuary (and later at the Dawnstar Sanctuary), sells four Deathbell, which restocks every 2 days.
 * An abundance of Deathbell can be found inside Shalidor's Maze.
 * A few Deathbell plants can be found on a path from Chillwind Depths to a small camp.
 * There are a few plants, as well as several loose ones, in High Hrothgar.
 * There is an abundance of plants growing outside of Folgunthur.
 * Some can be found by the tomb entrance to the Thieves Guild.
 * Plenty can be found inside Forelhost where the alchemy labs are. (They were used to poison all the followers of the Dragon Cult.)
 * Many are found in Forsaken Cave west from Windhelm.(only during quest "White phial")
 * There is a single Deathbell to be found in the garden next to Honeyside, a house you can purchase in Riften.
 * A few are found in Jorrvaskr
 * One plant found between Ustengrav and Windstad Manor
 * In, several can be found in Castle Volkihar growing in he castle as well as some sold by the Alchemist. However, if you did not side with Harkon at the end of Bloodline, they will be marked for steal, along with all other items in Castle Volkihar.
 * At least three can be found south of Ustengrav.

Damage Health

 * Crimson Nirnroot
 * Ectoplasm
 * Emperor Parasol Moss
 * Falmer Ear
 * Human Flesh
 * Human Heart
 * Imp Stool
 * Jarrin Root
 * Nightshade
 * Nirnroot
 * Poison Bloom *
 * Red Mountain Flower
 * River Betty *
 * Skeever Tail
 * Small Antlers *
 * Troll Fat
 * Void Salts

Ravage Stamina

 * Bee
 * Berit's Ashes
 * Bone Meal
 * Honeycomb
 * Scathecraw
 * Spawn Ash
 * Thistle Branch

Slow

 * Burnt Spriggan Wood
 * Large Antlers
 * Poison Bloom *
 * River Betty *
 * Salt Pile
 * Trama Root

Weakness to Poison
* multiple effects
 * Abecean Longfin
 * Bleeding Crown
 * Chaurus Eggs
 * Giant Lichen
 * Pine Thrush Egg
 * Sabre Cat Tooth
 * Small Antlers *

Trivia

 * The name of this ingredient is quite probably based on the Bluebell flower, with "Blue" being replaced by "Death" based on it's use with poisons.