Avalas

Avalas, also known as the Battleplains, was the first layer of Acheron. It contained the divine realms of Bane, Gilgeam, Gruumsh, and Maglubiyet, according to the Great Wheel cosmology model.

Geography
Of all known layers of Acheron, Avalas contained the largest number of cubes, which ranged in size from cities to continents. The layer was also the most densely inhabited of the plane.

Collisions between cubes were constant, happening as frequently as once a week and sending resounding vibrations throughout the layer. The collisions also slowly eroded the cubes, destroying structures on the surface, carving canyons, and collapsing tunnels. Due to the very orderly nature of the plane, the cracks on the cubes' faces were always perpendicular, so large cubes always broke down into smaller cubes. For that reason, smaller cubes were typically the oldest, while larger ones were younger.

The layer was continuously replenished with new, featureless cubes that were generally avoided by other cubes' inhabitants due to their lack of food sources and places to hide in the event of a collision.

The Styx criss-crossed the layer, emerging from a crater on one cube, running for miles, draining down into another crater, and reappearing on a different cube entirely. Sometimes, it changed course and drowned whole cities, taking with it memories and lives. In other places, the river flowed through one cube's face only to plummet into another in massive―and deadly―waterfalls.

Divine Realms

 * The Black Bastion, realm of Bane.
 * Clangor, realm of Maglubiyet and his lieutenants Khurgorbaeyag and Nomog-Geaya.
 * Nishrek, realm of Gruumsh, Bahgtru, Ilneval, and Luthic.
 * Zigguraxus, realm of Gilgeam.

Notable Cubes

 * The Blue Cube, lair of the solitary blue dragon Teslor.
 * Reizmis, a cube located near the entry point of the Styx into Avalas. The river completely engulfed the cube in a waterfall, causing its material to rust and absorb some of its memory-stealing properties. The Doomguard held a mining facility deep within the cube, where they used the metal to forge consumptive burst weapons infused with negative energy.
 * Wreychtmirk, a cube along the Styx course that allowed travelers to accurately predict the river's destination. The Styx flowed from each of the cube's faces into a specific Lower Plane, causing each face to assume the plane's characteristics, so a passenger always knew where the river led from each face.