Doravelzog

Doravelzog, orcish for "gateway to the prison", is a demiplane of unknown creation between the Material Plane and Nadiria, the Plane of Darkness. It was accessible through the deepest mines of Aktempto, and it is said to be the location of Esturk's slumber.

Description

Far beneath in the deepest reaches of the Aktempto mines, the tunnels of the orcs reached a barrier of some kind. As they dug too deeply, an opening to a place between the Material Plane and Nadiria was reached. This passageway was later closed by the Zenethian Heroes, who collapsed the tunnel with arcane explosions.  
[...] the Heroes were led deep into the mines of Aktempto. The area changed deeper and deeper in until they felt they must have traversed beyond the world of Azimuth. In a spherical opening deep beneath the world, the party approached a precipice over endless darkness.
  The demiplane appears as a large spherical opening deep beneath the ground. It is a void with a radius of approximately one mile, and the edges are rough and natural stone.   On the side of the accessway, a descending pathway leads back and forth in tight turns down to a large precipice. This outcrop leads out towards the centerpoint of the space in a jutting triangle of stone.   Beyond this precipice, the space falls away to void and darkness.

History

The Third Age: The Age of Zenethia
At the end of the Great War, Zenthai, The Dragon King, and the Zenethian Champions battled Esturk, The World's End. Though Zenthai was wounded, Esturk was defeated and set to slumber beneath Tarteria through means unknown.  
Only those chosen six, and The Dragon himself know what transpired in Esturk’s fortress in the west. But when the final blow was struck, all those who remained across the world knew in an instant what had transpired. The Daemons were banished and the skies cleared from their unholy taint. Yet while the Champions returned, their Dragon King did not, mortally wounded in the final clash of gods. Esturk lay defeated, buried beneath the ground of the wildlands, and the Great Dragon retreated to the realm of Zenethia, to one day recover.
 
The Fourth Age: The Age of Shadow
At some point in the late Fourth Age, the mines of Aktempto would reach too deep, breaching Doravelzog.   At some point, Psaro the Manslayer approached the sleeping Esturk to propose an alliance to destroy the world. Esturk laughed Psaro away.   After partially awakening, the demonic forces of Esturk would emerge, starting the Tarterian War. The mines of Aktempto were overrun and the town was destroyed.   On 2 Avedar 4A 996, the Zenethian Heroes attacked Aktempto, entering the mines and Doravelzog, bringing battle to the Dark Champions and Esturk, The World's End. During the battle, Zenthai, The Dragon King, was slain and Esturk was set to slumber once more.  
The Fifth Age: The Age of Beginnings
In 5A 351, Doravelzog was listed in Maalik’s research into potential sources of residuum.
Type
Dimensional plane
Plane
Nadiria, the Plane of Darkness