Soul Cairn

A plane of Oblivion that holds trapped souls, visited in the Dawnguard questline.

Quests here

Beyond Death (Dawnguard): Starts when you step toward the portal at the end of Chasing Echoes. Reward: Elder Scroll (Blood) and the shout Summon Durnehviir.
Impatience of a Saint (Dawnguard): Speak to the soul of Jiub, who paces among the ruins of the Soul Cairn rehearsing his memoirs. Reward: Locket of Saint Jiub and a copy of Saint Jiub's Opus.
Find Arvak's Skull (Dawnguard): A soul near the entrance of the Soul Cairn runs up begging you to save his horse, Arvak. Reward: The spell Summon Arvak.
Summon Durnehviir (Dawnguard): After Beyond Death, Durnehviir waits near the Soul Cairn's exit and teaches you to call his name. Reward: All three words of Soul Tear.

Dur (Curse) of Summon Durnehviir: Taught by Durnehviir near the Soul Cairn's exit at the end of Beyond Death.
Neh (Never) of Summon Durnehviir: Learned together with the first word after Beyond Death.
Viir (Dying) of Summon Durnehviir: Learned together with the first word after Beyond Death.

Locket of Saint Jiub (Dawnguard) – Amulet: Jiub's reward for the ten pages of his opus in Impatience of a Saint.
Conjure Boneman (Dawnguard) – Conjuration: Lies in the Soul Cairn, in the middle of the ring of pathways south-west of the ninth page of Jiub's Opus.
Summon Arvak (Dawnguard) – Conjuration: Taught by the soul who owned the horse, once you bring him Arvak's skull in the Soul Cairn. There is no tome.
Conjure Mistman (Dawnguard) – Conjuration: Lies in the Soul Cairn, next to the seventh page of Jiub's Opus.
Conjure Wrathman (Dawnguard) – Conjuration: Lies in the Soul Cairn, in a building due south of the fifth page of Jiub's Opus.