Arcana's Heart (are-KAHN-aas Heart)
Geography
Calling Arcana's Heart big would be a massive understatement, even for a planet. This planet is so massive that instead of orbiting a sun, it has three suns orbiting it. These suns were named the Id, Ego, and Superego, after ancient psychologist Sigmund Freud's model of the human psyche. An equal distance apart, but the same distance from Arcana's Heart, they were named after their properties. Id is a violent sun, with high solar activity and millions of solar flares every second. Ego, the largest of the suns, stabilizes the orbits of the other two with its strangely shaped gravitational field. The Superego is a calm sun, emitting a constant, unchanging stream of solar energy. No flares or variations in Superego's activity have been recorded. Each of the three suns have their own Solar System.
The three suns orbit the planet on different axes spaced almost perfectly evenly from each other. Due to this, Arcana's Heart experiences daylight (almost) all the time, all over the planet. Every 7,000 pulses, the three suns' orbits temporarily distort due to Ego's gravitational effect on them slowly pulling them away from their orbit. During this event, the three suns align as they quickly fall back into place in their orbits. This alignment of the Suns is known as Pelor's Day. During this event, half of Arcana's heart receives harsh, strong sunlight, and the other half receives blistering cold. Pelor's Day lasts long enough for a full rotation of Arcana's Heart, so the whole planet experiences one day and night.
The many sharp changes in elevation across the surface of the planet seem nonsensical and chaotic from the surface, but when viewed from space, reveal runes, geometrical shapes, and other arcane symbols carved deep into the planet's surface. Due to every inch of the planet being hit by two suns all the time, the surface is extremely hot. However the deep valleys are almost entirely blocked from the sunlight, and due to the lack of an ozone layer like Earth's, heat easily escapes the planet. So the only source of heat is direct sunlight. As a result, these valleys are extremely cold. So the valleys are too cold, and the massive plateaus are too hot. Where are the homes and towns built? Where do things live?
On the cliffs...
Ecosystem
Organisms living below the habitable elevation must adapt to the extreme cold and lack of sunlight below, and those living above must adapt to the powerful and deadly heat and radiation constantly beaming down from the suns.
Localized Phenomena
The gases released by the frostmoss form a sort of blanket near the top of cliffs, creating a proxy greenhouse effect, however far less effective. Were it not for the constant production of oxygen by the frostmoss, oxygen would have to be artificially supplied for inhabitants.
There is no layer of protective gas at the top of the atmosphere, The only thing holding gases on the planet is its powerful gravity. Even then, gas rapidly escapes, but is soon pulled back in great winds of gas. However, these gas winds are random in content, size, and frequency. Hundreds of years can go without a wind, but that is very rare.
Fauna & Flora
The cliffs, right between the surface and the troughs, where the temperature is livable, is where most life is. Of course, life thrives on the surface and in the trenches. Extremophiles are a fact of life.
Such as the great Rayworms, who have developed a natural immunity to the intense heat and radiation from the suns. These "worms," which are much more like snakes, live off the energy granted by the ionizing radiation of the three suns.
The exact opposite of rayworms are ice carvers. Strange, cone-shaped creatures who burrow through the hard permafrost their entire life. They have tough, tungsten-based teeth for boring through the ice, and are completely blind, and deaf, relying on vibrations in the ice to observe their surroundings. Truly horrifying creatures.
What planet would be complete without flora? And there is plenty.
The Sky Lillies, also known as radtrees, are massive tree-like stalks which fan out to absorb the radiation from the suns, much like rayworms.. It is theorized and partially proven that rayworms and radtrees come from a common ancestor.
Deep in the depths of the icy trenches grow a strange, blue, bioluminescent moss. This moss, called frostmoss, or ice's carpet, despite having no method of generating heat or receiving energy from the suns, serves a different role as regular moss. It is a decomposer, breaking down dead ice carvers and releasing them as dense gases which rise up and form a blanket near the top of the cliffs. Oxygen is also released, and is held under the surface by the thick clouds of gas, visible from the surface as a navy blue fog.
Natural Resources
Strong magical crystals seem to grow from nothing deep inside the cold, rocky caves of Arcana's Heart. These crystals form from leftover ambient magic released by the billions of trillions of casters living on the planet.
Comments