Neltharion's Vault

Neltharion's Vault is a large cavern found in Highmountain.^[25, 40] It was here that the drogbar fitted the goblin-made plates to Deathwing. Stored here was the [Hammer of Khaz'goroth] and two sets of titan disks. With the help of Igrul the Scalebane, Huln Highmountain used the hammer to banish Deathwing to Deepholm.^[1]

The Slave Enclave leads to Obsidian Overlook, which lets non-dragons escape by flight path.

Notes

[Burning Plate of the Worldbreaker], which unlocks the Last Breath of the Worldbreaker appearance for the Protection Warrior's [Scale of the Earth-Warder] artifact, can be found in the piles of gold coins.
Before patch 7.3.5, The Grey One could be found at the end of a long path full of Goldsnuffle kobolds.
In the beta, lying forgotten in a corner of Neltharion's Vault was a "Dragon Soul Experiment" object that was removed.

Speculation

This article or section includes speculation, observations or opinions possibly supported by lore or by Blizzard officials. It should not be taken as representing official lore.

This may be the lair where Neltharion hid the Demon Soul during the War of the Ancients.^[2] It is extremely likely that this is a section of Neltharion's Lair.