One of the basic building blocks of the cosmos.
The Elemental Plane of Fire was an Inner Plane or Elemental Plane of the Great Wheel cosmology and the World Tree cosmology models. After the Spellplague, the Elemental Plane of Fire collapsed into the Elemental Chaos, mixing with all the other Inner Planes. Fire is one of the four elements and two energies that make up the known universe and more than any other element has fascinated sentient beings since the beginning of time. The flickering of a candle, the spark of a flint and steel, or the dying embers of a campfire, all have the potential to grow and engulf the world in flame—can a drop of water, a breath of air, or a mote of dust do the same? Elemental fire is pure flame that does not require air or fuel to burn and can take on a solid, liquid, or gaseous state, yet it will ignite and consume anything flammable and unprotected from fire.
According to the Great Wheel cosmology model, the Elemental Plane of Fire could be reached via the Ethereal Plane, an adjacent elemental plane, or by an elemental vortex. Two known vortices to adjacent elemental planes were the Iron Crucible that led to the Elemental Plane of Earth and a vortex to the Plane of Air atop Jabal Turab, the Mount of Dust. If traveling through the Deep Ethereal, a red curtain of vaporous color indicated the boundary of the Plane of Fire's Border Ethereal region. Once in the Border Ethereal, a traveler could observe the Plane of Fire and be detected by its denizens. Using the spherical model, this plane was adjacent to the para-elemental planes of Smoke and Magma and the quasi-elemental planes of Radiance and Ash. Elemental vortices could occur wherever a high concentration or nearly pure form of an element was found, and could be temporary or permanent. Vortices to the Plane of Fire could often be found in pools of molten lava or the upwelling of magma in active volcanoes. Temporary gates could be created by the plane shift spell or the abilities of high-level druids.
As described by the World Tree cosmology model, the Astral Plane connected all planes with the Prime Material Plane and the Ethereal Plane was only used for journeying between locations on the Prime. The Elemental Plane of Fire was not connected or coterminous with any other elemental plane. The spell astral projection could be used to reach the Plane of Fire via a fire opal color pool. Additionally, the gate and plane shift spells could be used to open a temporary portal to this plane. To reach the Plane of Fire by means of a plane shift spell required a copper fork tuned to the note of A.
Arriving on the Plane of Fire was like stepping into the flaming maw of an ancient red dragon; if one didn't have protection or immunity from temperatures high enough to melt stone then death was swift. The following discussion assumes a visitor and all their clothing and gear had this capability and either did not need to breathe or could compensate for a superheated, often toxic atmosphere that could immolate one from the inside (think cloudkill plus incendiary cloud). In general, the more fluid the elemental fire, the hotter it was and the more damage it did to unprotected material.
Unlike the other three elemental planes, the Plane of Fire had normal gravity and a landscape, although most of the "ground" was made primarily of loosely packed elemental fire and felt like walking in a swamp of hot coals. The rivers and oceans were filled with a more liquid version of the same stuff and swimming worked normally as a mode of transportation. Non-native flying creatures found the atmosphere thin and therefore did not have their usual speed or maneuverability. Visibility was hampered by the smoke coming off the flames engulfing, but not consuming, nearly every solid, liquid, or gas (and creature) on the plane. What one could see was usually distorted by heat ripples. Geographic features such as hills, mountains, and cliffs did not have a geologic lifespan because even the more solid areas slowly moved like a subterranean magma flow as seen on the Prime Material Plane. Permanent physical structures were very rare.
If the Plane of Fire had weather, it was of course hot and deadly. Rains of hot ash moved about like thunderstorms, threatening those on or near the ground with hot embers and blinding ash. Those in the air had to watch out for clouds of superheated steam blowing around and condensing scalding water on exposed surfaces. The water quickly evaporated and the cycle began anew. Easier to avoid but just as deadly were the rivers of magma and "firefalls". Matter from other planes either evaporated, burned to ash, or melted into magma. Magma mixed with elemental fire formed a rapidly moving, incredibly hot slurry that coursed around the terrain and occasionally cascaded over a cliff edge to create a firefall, often manifesting an elemental vortex in the spectacular display. The Great Wheel cosmology model explained these hazards and others as pockets of elements from all the other elemental, para-, and quasi-elemental planes that got sucked into the Plane of Fire and cast adrift to face their fate. Cold spots could even be found where it felt like the middle of the Raurin desert at midday. With a guide, a traveler could approach the borders with the other planes, where the smoke finally choked out the fire, or the fire became nothing but cold ash, or the molten earth absorbed the fire, or the radiance ultimately outshone the fire.
The dangers of the plane could not be overstated, but those that survived the trip saw wonders and beauty at nearly every turn. Flame colors spanned the rainbow, from the vermilion of a forge hearth to the yellow-white of heated iron, from the blues and greens of alchemical reactions to the familiar candle-flame yellows and oranges. The conflagration formed fountains, jets, sheets, rivers, waves, walls, rains, cascades, clouds, swirls, and pits of brilliant incandescence on a scale found nowhere else.
City of Brass
One famous refuge from the destructive heat was the City of Brass, home of the efreet. At the will of the grand sultan, the city was protected from the pervasive smoke and flames, and visitors enjoyed unrestricted vision and uncomfortable yet tolerable temperatures, but walls and surfaces were still hot enough to burn unprotected flesh on contact. The city sat in a bowl of golden brass 40 miles (64 kilometers) in diameter that floated about the plane or hovered over a huge disk of obsidian that was cracked from the heat. Architecture included soaring towers, grand minarets, and everything from tool sheds to palaces made of brass. The treasure vaults of the grand sultan, and his wrath at any who attempted to acquire even a single piece, were legendary.