Daemon Angren

Daemon Angren is a fortress of Mordor appearing at TheLandOfShadow.com appearing on the map at the place a mountain simply named Amon Angren is on a rare map of Mordor by Tolkien.

However Daemon Angren was a stronghold upon that mountain made by one of the Nine Ringwraiths when they returned to Mordor before Sauron did, to rule over southern Mordor below the Mithram Spur, watching Nurn.

Etymology
Daemon Angren is Sindarin; "dae-" meaning "shadow", "amon" meaning Hill, and "Angren" meaning "iron", it probably is supposed to mean Iron Shadow-hill.