The Planes

Most planes are immeasurable, so immense they're impossible to quantify. Which immeasurable planes, if any, are infinite is a subject of debate among philosophers and scholars alike. Since so many planes are immeasurable, those planes omit a scope trait. Otherwise, the plane likely has either the finite or unbounded trait.

Finite: Finite planes consist of a limited amount of space.

Immeasurable: Immeasurable planes are immeasurably large, perhaps infinite.

Unbounded: Unbounded planes loop back on themselves when a creature reaches the plane's “edge.”

Many planes have unusual gravity.

Normal: Bodies of great mass are the centers of gravity, and objects fall toward those centers with a measured amount of force relative to the size of the body.

High Gravity: As in normal gravity, bodies of great mass act as centers of gravity, but the force relative to the size of the body is greater than in the Universe. The Bulk of all creatures and objects is doubled, meaning creatures acclimated to normal gravity can carry only half as much. Creatures used to normal gravity move at half Speed and can jump only half as high and far. Physical ranged attacks are impossible beyond the third range increment (instead of the sixth). Creatures that fall in high gravity take bludgeoning damage equal to the distance they fell.

Low Gravity: As in normal gravity, bodies of great mass act as centers of gravity, but the force relative to the size of the body is less than in the Universe. The Bulk of all creatures and objects is halved, meaning creatures acclimated to normal gravity can carry twice as much and jump twice as high and far. Physical ranged attacks are possible up to the twelfth range increment (instead of the sixth). Creatures that fall in low gravity take no damage for the first 10 feet of a fall, and then take bludgeoning damage equal to a quarter of the remaining distance it fell.

Microgravity: There's little to no gravity on this plane. Creatures float in space unless they can push off a surface or use some force to propel themselves throughout the plane.

Strange Gravity: All bodies of mass are centers of gravity with roughly the same force. A creature can stand on any solid objects that's as large as or larger than themself.

Subjective Gravity: All bodies of mass can be centers of gravity with the same force, but only if a non-mindless creature wills it. Unattended items, objects, and mindless creatures treat the plane as having microgravity. Creatures on a plane with subjective gravity can move normally along a solid surface by imagining “down” near their feet. Designating this downward direction is a free action that has the concentrate trait. If suspended in midair, a creature can replicate flight by choosing a “down” direction and falling in that direction, moving up to their Speed or fly Speed. This pseudo-flight uses the Fly action.

Time flows differently on many planes.

Normal: Time passes the same way it does in the Universe. One hour on a plane with normal time equals 1 hour in the Universe.

Erratic: Time slows down and speeds up, so an individual might lose or gain time as they move between planes. When a creature moves from a plane with erratic time to one with normal time, roll a DC 11 flat check. Creatures that leave an erratic time plane together share the same result.

Flowing: The flow of time is consistently faster or slower. A creature might travel to one of these planes, spend a year there, and find that only an hour passed in the Universe; alternatively, they might spend a minute on this plane and find out an hour passed in the Universe.

Timeless: Time still passes, but the effects of time are diminished. Creatures on these planes don't feel hunger, thirst, or the effects of aging or natural healing. The effects of poison, diseases, and other kinds of healing might also be diminished on certain timeless planes. Spell energy and other effects still dissipate, so the durations of spells and other effects function as normal. The danger of this trait is that when a creature leaves a timeless plane and enters a plane with another time trait, the effects of hunger, thirst, aging, and other effects slowed or arrested by the timeless trait occur retroactively in the instant of transition, possibly causing the creature to immediately starve or die of old age.

This trait describes how easily the physical nature of the plane can be changed. The Universe is considered the norm for its residents, but other planes can warp through the plane's own sentient designs or be manipulated by extremely powerful creatures.

Normal: Objects remain where they are (and what they are) unless affected by physical force or magic. Creatures can change the immediate environment as a result of tangible effort, such as by digging a hole.

Metamorphic: Things change by means other than physical force or magic. Sometimes spells have morphic effects. Other times, the plane's nature is under the control of a deity or power, or the plane simply changes at random.

Sentient: The plane changes based on its own whims.

Static: Visitors can't affect living residents of the plane or objects the denizens carry in any way. Any spells that would affect those on the plane have no effect unless the static trait is somehow removed or suppressed.

Planar essence traits describe a plane's fundamental nature. For example, many of the Inner Sphere's planes are infused with an element or energy, each of which affects magic on those planes, and the Netherworld is awash with shadow. Outer Planes are fundamentally made up of quintessence, a philosophically aligned material with infinite potential for shape and state that conforms to powerful and prevailing beliefs.

Air: Planes with this trait consist mostly of open spaces and air of various levels of turbulence, though they also contain rare islands of floating stone and other elements and energies. Air planes usually have breathable atmospheres, though they might include clouds of acidic or toxic gas. Earth creatures often find themselves at a disadvantage within air planes, as there's little solid ground for them to gain their bearings, which tends to at least make them uncomfortable.

Earth: These planes are mostly solid. Travelers arriving upon an earth plane risk suffocation if they don't reach a cavern or some other air pocket within the plane's solid matter. Creatures who can't burrow are entombed in the plane's substance and must attempt to dig their way toward an air pocket. Air creatures are ill at ease, as they rarely have the space to move freely through even the loftiest warrens.

Fire: Planes with this trait are composed of flames that continually burn with no fuel source. Fire planes are extremely hostile to non-fire creatures. Unprotected wood, paper, cloth, and other flammable materials catch fire almost immediately, and creatures wearing unprotected flammable clothing catch fire, typically taking 1d6 persistent fire damage. Extraplanar creatures take moderate environmental fire damage at the end of each round (sometimes minor environmental damage in safer areas, or major or massive damage in even more fiery areas). Ice creatures are extremely uncomfortable on a fire plane, assuming they don't outright melt in the heat.

Metal: These planes consist of chaotic and shifting structures and oceans of metal. Metal planes tend to exist in a state of change and decay, leaving plentiful pockets of air for visitors to breathe or move within. Creatures unlucky enough to be entombed in the plane's substance risk suffocation if they can't phase through metal. Wood creatures find the lack of stability and soil on a metal plane disconcerting and often fail to thrive in such environments.

Water: Planes with this trait are mostly liquid. Visitors who can't breathe water or reach an air pocket likely drown. The rules for aquatic combat usually apply, including the inability to cast fire spells or use actions with the fire trait. Creatures with a weakness to water take damage equal to double their weakness at the end of each round.

Wood: These planes consist of trees and other flora latticed in organic patterns. Wood planes are often perfectly constructed to match their desired purpose or environment but aren't usually outright hostile to visitors.

Shadow: Planes with this trait are umbral with murky light. In the Netherworld, the radius of all light from light sources and the areas of light spells are halved.

Void: Planes with this trait are vast, empty reaches that suck the life from the living. They tend to be lonely, haunted planes, drained of color and filled with winds carrying the moans of the dead. At the end of each round, a living creature takes at least minor void environmental damage. In the strongest areas of a void plane, they could take moderate or even major void damage at the end of each round. This damage has the death trait, and if a living creature is reduced to 0 Hit Points by this void damage and killed, it crumbles into ash and can become a wraith or other undead creature.

Vitality: These planes are awash with life energy. Colors are brighter, fires are hotter, noises are louder, and sensations are more intense. At the end of each round, an undead creature takes at least minor vitality environmental damage. In the strongest areas of a vitality plane, they could take moderate or even major vitality damage instead. While this might seem safe for living creatures, vitality planes present a different danger. Living creatures regain an amount of HP each round equal to the environmental damage undead take in the same area. If this would bring the living creature above their maximum HP, any excess becomes temporary HP. Unlike normal, these temporary HP combine with each other, and they last until the creature leaves the plane. If a creature's temporary HP from a vitality plane ever exceeds its maximum HP, it explodes in a burst of overloaded vitality energy, spreading across the area to birth new souls.

The planes of the Inner Sphere form the heart of the cosmos. They're the home of mortal life, the focus of divine attention, the source of mortal souls, and the origin point of the great cycle of quintessence that fuels the motions and stability of reality itself. Arranged in a nested series of shells, like layers of an onion, the planes of the Inner Sphere include, from outer to inner: the elemental planes of fire, earth, metal, water, wood, and air; the mortal galaxies of the Universe; and at the very core of this cosmological ensemble, the raw forces of creation and destruction of Creation's Forge and the Void overlap the Universe.

At a minimum, each Transitive Plane coexists with one or more other planes, a relationship oversimplified by stating that Transitive Planes are just used to get from one plane to another. The Drift has mysterious one-way connections to every plane, though those same planes can't access the Drift except through the same technology necessary by those in the Universe. The mists of the Ethereal Plane overlap the planes of the Inner Sphere, while the Astral Plane borders every other plane in existence like the backstage of the cosmos. Bright and dark mirrors of the Universe, the First World and the Netherworld overlap the mortal world, albeit often in bizarre ways such that a short distance in one might be a vast gulf in the other. The daring, wise, or desperate can utilize these planes to bypass barriers in the Universe or rapidly cross vast distances through much swifter travel.

The planes of the Outer Sphere are the manifest realms of philosophy: good and evil, order and change, faith, and their admixtures, populated by celestials, fiends, monitors, and others who promote these moral concepts. These planes are the backdrop upon which the mortal afterlife reaches its apparent conclusion, and the end destination of the River of Souls. The Outer Planes are regions of stability adrift in the raw, chaotic quintessence of the primordial Maelstrom, its tides forever gnawing at their edges even as mortal souls sustain them. The Outer Rifts manifest as cracks in the Outer Sphere's fabric. Rising from the metropolitan Axis is the Boneyard's spire, the location where mortal souls are judged and then sent to their final destinations, be they reward, suffering, or oblivion. The Outer Planes are places of majesty, wonder, terror, and danger outstripping anything mortal adventurers might encounter anywhere else.

Existing in the metaphorical space between the Transitive Planes and smaller, finite demiplanes, dimensions are a category unto themselves, defying the neat categorization of planar scholars and adventurers. Seemingly infinite in scale, not necessarily spatial in the same way as a plane, and overlaying every other plane at once—including one another—dimensions and planes are most significantly differentiated in how each of them breaks the commonly held rules of the other.