The Twisting Nether is is a dimension consisting entirely of energy that exists alongside the Great Dark Beyond. The Twisting Nether composes entirely of energy just as the Great Dark Beyond consists entirely of matter. The Twisting Nether is immaterial whereas the Great Dark Beyond is material. The Twisting Nether traverses the entirety and eternity of material space, and intersects every world in the universe.
The Twisting Nether transcends all realities and is normally imperceptible to mortal races. The Nether is affected by the worlds that are intersected by it and the Nether affects these worlds in turn. In the Twisting Nether, every thought becomes a physical construct, every metaphor becomes a literal meaning. It is possible to enter the Twisting Nether as a material being, but few who do so have ever returned. The Twisting Nether is also populated by beings that consist entirely of energy and the Twisting Nether is their native home. Creatures such as Mana Wyrms are common examples of the more benign creatures native to the Nether. The Twisting Nether is also traversed by the Burning Legion and the myriad Demons of the universe, and is their primary method of travel between worlds as well as their home dimension when between contests. As Demons are composed entirely of energy, Demons in the Nether are much stronger than they would be on the material plane of the Great Dark Beyond. Being in the Nether also makes a Demon vulnerable however, as in the Twisting Nether, a Demon may be killed permanently without chance of regeneration.
The Twisting Nether is often assumed to be the realm of the Burning Legion. While this is true in that it is their native plane of existence, the Burning Legion does not span the entirety of the Twisting Nether, and their Fel corruption has not yet corrupted the entirety of the Nether. Vast expanses of pure Nether energy exist within the Twisting Nether which are compromised of concentrated Mana. This raw energy was used by almost every mortal race as well as the Titans to develop their first magical abilities. Without the Twisting Nether, there would be no magic. Other beings beside Demons also traverse the Twisting Nether. The dimensional ships utilized by the Naaru traverse the Twisting Nether, the Ethereal race of K'aresh has mastered a form of safe to use travel through the Twisting Nether, as well as the portals used by Mages, Warlocks and spell casters that travel between worlds. Temporary portals opened through the Nether such as from Azeroth to Outland traverse through the Twisting Nether using the Dark Portal as a shortcut. A more stable, permanent portal can be kept open and active through capitalizing on rifts that form naturally throughout the Great Dark Beyond.