Bhaelnarok

Behold a realm of blazing fire! Where ashen coated statues of great daemons hold aloft the urns of tormented souls, seeping lava into gulfs underneath windling bridges and stairs built by hunchbacks with brittle bones!
Behold jagged mountaintops with dark coated tops of obsidian, where once lava would spout from volcanic rage and oozing wounds in the soil. See them blaze around cities and fortifications created from steel and gold, where the denizens of Muspelandr roam!

Geography

Red is the soot and dust which covers the floor of the plain. Stretching like veins from it's soil follow lakes of volcanic ascent, a mix of molten rock and pure infernal fire makes up what would have been water. Instead, freshwater pumps from great geysers that are a constant boiling hot. Formed from the great temperatures and presure of bubbling meltingpot of minerals that hide underneath the crust of earth.
To wander Bhaelnarok, or Muspelandr as the Scarnzans often come to calm the plane, is near certain death. Only the air far above the grounds is even breathable for a longer time, as soot and ash linger on the bottom and both blind and suffocate those who spend too much time outside of the great keeps which loom above.
If one was to look up, the sky is constantly moving like fluid due to the sulphuric acids that rise from the lava seas. Sickly yellow clouds cover most of the pinkred above and ten suns shine with appocalytpic delight that could blind any man, as if the horrid smell of molten chemicals was not enough.

Ecosystem

Even in the most infernal of hells, life must still be able to somehow cope unless it's to be a forgotten waste. Hence lifeforms still live within the seas of lava. Feasting on minerals while their bodies are not only capable of withstand the heat, but radiates something even hotter to ensure the false waterbodies still flow.
From the rich soil, forests yet grow to shroud and protect it's shade from the deadly flames. Enabling smaller critters to feed and hide, while the beasts beyond it's crowns can wander the wastelands on the hunt.

Ecosystem Cycles

Ever so often, parts of the landscape is torn sundered by the raging forces of nature. While these events do not happen in timed cycles, many hunting beasts need to change preying grounds, as parts of forests are both destroyed and re-emerge from the ashes of old crust reinvigorated by fresh soil. It also happens that lakebeds of lava dry up and that new pools form as the volcanic activity goes ever onward.

Localized Phenomena

One of the most deadly phenomena that exist, are the combination of firestorms and acid rain. It is merciless, can scorch away at the very landscape and make the soil underneath deadly to walk for hours after the rain has ceased to pour. Nor is it a phenomen that can be easily calculated to when and where it will hit. It is an erratic force that strikes from nowhere.
Lightning is also far more dangerous in Bhaelnarok than what it would be in the mortal realms. It hits without rhyme and reason, due to how foul the air is. A few more than three thousand lightning bolts will hit the plane within every mortal day and night.

Fauna & Flora

Within Bhaelnarok there are only three different types of forests. Well, the first is technically a march named Ebonwillow march after the only tree that grows there. This boiling swamp is home to the Helltoad, Ashcarrion and Salamander.
The first proper forest is a so called cinderwood forest, and is home to the Volcanic Fox, Sootbear and Cindaer. All which ironically are full herbivores. The cinderwood is also the more temperate of the two forests, and has an ability to siphon the acidic rain and turn it into fresh water within the leaves.
The second forest is the shadebough which is the most cool area of them all, even though the creatures which live here are only smaller insects that are harmless and hide underneath the ground.
Other predators that live within the harsh climates outside are, but not limited too, the pheonix, craghulk and hellhound who from time to time prowl these three lush wood areas for a snack. Then there are the Hellboar and Deathmantid who more or less feed purely from cannibalism, or corpses of bonewyrms and spooks that are both flying creatures which feed directly from the minerals within the soil.

History

The hellscape of Bhaelnarok is since long ruled over by creatures of soot and fire. Giants that walk the lands as casual as if they were on a vacation rule here, and were the founders of the great stone constructions of wrath, rage and ire that watch over the demons that reside within it's fortifications.
Many believe that Bhaelnarok was in fact a whole different world, once upon a time which was ruled by some predecesor race to the giants. A world that came to be the original hell as it was completely obliterated by war and conquest among it's titanic inhabitants. Something which the many weird statues and ruins which stain the landscape would portray in a light of truth. Though little is known about these lost cultures, the human invaders of Feuvillion work side by side with Silveron to unravel the secrets of hell.

Tourism

Bhaelnarok is the first of the three hells which have conquered mortal outposts within them. Though it's not exactly a nice place nobles come to host extravagant parties, there are scientists, generals and wizards who willingly go on trips to the plane of infernal fires to study their creatures and soil, both for the development of civilization, their warmachine against the demonic threat and to fight against it's nature to forcibly bend parts of it to be habitable.
It's also common that the most extreme of adventurers make pilgrimages to the infernal lands in hope of raiding their fortifications and enslaving immortal souls of higher standing. Demons are after all highly sought after by different temples as cleansing experiments, or their souls can be used to force devils to make deals with them, in the mortals favour, in order to get their high ranked officers back.

The fifth plane of the twelve hells

Type

Dimensional plane