Pandemonium

"My journey to Pandemonium has allowed me to see a new world &mdash; one that is almost too fantastic for mortal eyes. The ancient battlefields stretch before me, a desolate space that is occupied by small, scouring beasts. They search the lands endlessly, thriving off the magic that lingers from battles long past."

- Deckard Cain

Pandemonium is one of the realms of Creation.

Lore
Pandemonium lies at the epicenter of reality. It is the "scar" of the universe's violent birth due to the battle waged between Anu and the dragon Tathamet. It possesses "warped reality" traits. The realm acts as a crossroads for the domains of all beings, and the core of Pandemonium acts as a nexus between the High Heavens and Burning Hells. It is a seat of great primal energy that keeps forming new land near its core, while around its edges pieces are constantly breaking off in an eternal loop of creation and destruction. Pandemonium has some native races, but these beings are not human, nor do they operate like humans. Pandemonium is a realm beyond human understanding. Pandemonium is a vast, chaotic and harsh realm, and its inhabitants must be resourceful to survive.

The Eternal Conflict
At the center of Pandemonium lay the Worldstone. It was for this object that the Great Conflict was waged by angels and demons and consequently, most of the conflict was fought within Pandemonium itself. Ownership of Pandemonium alternated between angels and demons many times and due to the realm's "warped-reality" traits, Pandemonium has taken on the traits of the denizens of both Heaven and Hell.

With the disappearance of the Worldstone through the actions of Inarius and Lilith, the Great Conflict wore down, and the attentions of Heaven and Hell were drawn to Sanctuary. Yet even now, the scars of conflict still remain&mdash;ruined war machines are found throughout the landscape, and the bodies of fallen demons remain in Pandemonium. Some have been there for so long that they have been subject to petrifaction. Likewise, fortresses built by angels to ward off demons have long been abandoned, and demons remain in 'time traps' that angels set up for them. Some of Pandemonium's denizens have moved into the abandoned garrisons once maintained by the Heavenly Host. Additionally, some demons remained behind in the realm, unwilling to return to Hell, per being so addicted to violence.

Reaper of Souls
During the End of Days, Malthael took the Pandemonium Fortress as his own. This forced the Nephalem to travel across Pandemonium to the fortress, before finally entering it and slaying the fallen angel.

Diablo II
The Pandemonium Fortress is visited in Diablo II, but the realm itself is otherwise unavailable.

Diablo III
The realm of Pandemonium, as well as the above-mentioned fortress, is visited by the Nephalem during the later portion of Diablo III: Reaper of Souls.

Development
Blizzard Entertainment has long planned on visiting the realm, but it is their approach that Diablo expansions be more self-contained than core installments. As such, the in-game debut of Pandemonium was reserved for an expansion appearance. It was intended that Pandemonium look like no location on Sanctuary. It was decided that Pandemonium had to epitomize the nature of the Eternal Conflict. Some challenges were faced when conceptualizing the realm, as they didn't want it to look too futuristic.

The environmental effects of Pandemonium were designed to be a reflection of Malthael; Logs, chests, and barrels, evaporate once destroyed. it has been suggested that this is to reflect the idea of them barely clinging to the corporeal realm. Neal Wojahn has likened the effects to the burning of paper.

Structures

 * Abandoned Siege Camp
 * Hideout of the Lost Legion
 * Infested Ruins
 * Halls of Pandemonium
 * Lair of the Prophet
 * Pandemonium Fortress

Other

 * Battlefields of Eternity
 * Crag of Eternity
 * Forgotten Battlefield
 * Path of War
 * River of Souls
 * The Ram