Mystic dimensions are realms whose fundamental properties are governed by magical energies as opposed to laws of physics. Magic can be practiced in mundane physical realms, such as Earth, though it is generally the exception rather than the rule.
All the dimensions are reachable at any time from anywhere, if a traveler is powerful and knowledgeable enough. For those exploring the planes for the first time or in need of a little help, there is a specific route that makes the journey less impossible. There are barriers that restrict movement between certain realms, creating subsets: The Inner Planes, the Outer Planes, the Splinter Realms and the Far Realms, but passing within the subsets, such as between two realms in the Inner Planes to another of the Inner Planes, is comparatively simple. There are four known levels/subsets of planar groupings:
The INNER PLANES are a series of dimensions that are closely connected to the Earthly plane. Some are inhabited and/or have been created by pantheons of gods worshipped by the inhabitants of Earth (such as Asgard and Olympus), others are ruled by beings such as wizards or dragons or ducks. They may seem remarkably different from our own, but they are composed of the same basic elemental components (earth, air, fire, water) that make up the physical planes. They are generally similar in appearance to Earth's dimension and obey most of the same physical laws because they all were formed with materials from the Earthly plane.
The first four Inner Planes were created by the four surviving Elder Gods, Chthon, Gaea, Oshtur and Set. When Atum banished Set and Chthon from the Earthly plane, they created dimensions very close to it in order to continue to influence things. Using their powerful magic to evolve and shape the existing elements, Set raised the Serpent's Sea and Chthon conjured the Flickering Realm. Oshtur had left Earth of her own accord tens of thousands of years before the conflict to explore the stars and other dimensions. When Oshtur returned to Earth and learned what had happened, she created a stronghold on the Astral Plane and went into voluntary exile rather than weaken the banishment spell and leave Gaea vulnerable. So that she might visit her sister more easily, Gaea also created an extradimensional home for herself called Avalon.
The Crossroads There is deep enmity between Set and Gaea, Chthon and Oshtur, but they identified the Crossroads as "neutral grounds" where they could meet. Accessible from everywhere, if you just know which door to open or what hole to crawl through, the Crossroads can sometimes be difficult to leave. Wizards have spent decades wandering back and forth between the signposts. "May you meet yourself at the Crossroads" is a favorite magician's curse.
The Astral Plane (The Realm of the Mind, the Temple of Oshtur) An abstract dimension that is shaped by the minds of those present, it is fairly easy to access, and some non magical telepaths can travel there.
Avalon (The Golden Forest, the Bosom of Gaea) Much like Earth of millennia past, Avalon is lush and green, filled with magical beings like faeries, elves and trolls.
The Serpent's Sea (Here There Be Monsters, the Coils of Set) Set's insatiable hunger ripples through this abyss of tears and cold blood. The Sea's shores ebb and flow with Set's own power. At its peak, when Set's wizards and lizards ruled the Earth, the Serpent's Sea was practically impossible to cross. Set's recent defeats have caused the Sea to recede considerably.
The Flickering Realms (Dimension of the Darkhold, The Dark Heart of Chthon) There is no map of the Flickering Realms because the landscape is constantly changing. A traveler might cross sands, then swamps, next snow, and then stone. What's more, the stone may bleed and the snow might burn like fire. The only constant here is danger. The N'Garai's dimension is inside of this one, and the demons are everywhere.
The God Realms Over the millennia, many other deities and demons have created and/or inhabited their own realms to the Inner Planes. The God Realms were created by Earth's deities who wished to be close but separate from their worshippers. These include Alchera (Aboriginal), Ama (Amatsu-Kami/Shinto/Japanese), Asgard (Asgardians/ Norse), Dilmun (Annunaki/Mesopotamian), Elysium (Yazatas/Zoroastian/Persian), Ergenekon (Tenger/Mongolian), Giizhigong (Anasazi/Native American), Hawaiki (Akua/Oceanic), Hanan Pacha (Apu/Inca), Heliopolis (Ennead/ Heliopolitans/Egyptian), Kaluwalhatian (Diwatas/Fillipino), Nirvana (Daevas/Hindu/Vedic), Olympus (Olympians/ Graeco-Roman), Orun, the Great Beyond (Vodū/African), Quidlivun (Inua/Northern), Shinshi (Shin/Korean), Svarga (Dievas/Russian/Slavic), Taivas (Jumala/Finnish), Ta Lo (Xian/Taoist/Chinese), Tir na nÓg (Otherworld) (Tuatha de Danaan/Celtic), Topán, the Floating World (TĒteoh, Aztec), Upperworld (Ahau/Maya).
In addition, there are many other Inner Planes that have been created by powerful demons (Bad Lands) or by sorcerers (Bazaar at the End of Reason) for various purposes. Some of these realms include:
Bad Lands - Mystical realm created by the Demon-Bear, resembles the American Southwest.
Bazaar at the End of Reason - Pocket realm containing a city where sorcerers can ply their trades and sell their magic wares to visitors; populated by humanoid sorcerers, aliens and extradimensional beings.
Biphasia - World divided into realms of darkness (Shadow-Realm) and light (Searland), balance sustained by Delandra the Half-Queen.
Black Sea (People of the Black Sea) - Undersea world ruled by telepathic natives who claim to have ruled Atlantis in the past until forced to flee from religious persecution.
Cloudsea - Mystical world of floating landmasses within a breathable atmosphere. Home of the sorcerous council the League of Three Threes.
Katharta - The home to Korrek the Barbarian is an archetypical world of barbarians and sorcery, covered with purple and gold foliage
Land of Legends - Mystic realm to which beings who have become American legends are brought; landscape changes to conform with the America of its inhabitants.
Mindscape - Home to the Sleepwalkers. Connects the astral realm to the Dreamscape.
Weirdworld - Home to the elves Tyndall and Velanna, this mystic realm is inhabited by variety of magical beings, the most common of which appear to be elves or dwarves.
The OUTER PLANES (The Consecution of Colours) - In the Outer Planes the laws of the physical world fall away, revealing a landscape of colorful abstractions. The air, the land, the trees and all the material in these dimensions appeared to be composed of mystic radiant essences. Unlike those of the Inner Planes, the residents of the Outer Planes are not generally connected to or concerned with what happens in Earth's dimension.
The Prismatic Bridge of Asbru - The Inner Planes are separated from the Outer Planes by an enormous invisible barrier. Brona's Barrier (named after its discoverer, Brona the Enchanter) made travel beyond the Inner Planes nearly impossible. An old story says that once upon a time the spirit forms of two creatures, one from the Inner Realms and one from the Outer Realms, made contact and fell in love. Longing to touch, the two tried and tried to pierce the Barrier, but could not. They found a handful of wizards adept enough to pass through, but none strong enough to bring another. One of these wizards was also the Architect who had built the Rainbow Bridge, Bifrost. The two promised they would pay any price if he could build a way across the Barrier. As is often the case in such stories "the price" was steep. To complete the magic bridge the Wizard needed "two souls who long to touch." So, the couple died, never having seen each other. However, their spirits are joined together for Eternity inside the Bridge of Asbru.
Crimson Cosmos - In this harsh and beautiful realm, scarlet deserts lie in the shadows of ruby volcanoes billowing rust-colored ash into a sky that seems perpetually caught in a breathtaking sunset. The powerful entity Cyttorak rules this dimension and a path to it from Earth's Dimension lies within the mystic artifact the Crimson Gem of Cyttorak. The mystic realm known as the Crimson Dawn is adjacent to the Crimson Cosmos, though the nature of their connection is unrevealed.
The Purple Dimension - Immense purplish mountain ranges jut majestically from vast plum-colored plains. Surreal geological formations and powerful magic gems are almost common in this dimension, ruled by the greedy and domineering Aggamon.
Ikonn - The dimension of Ikonn is an ever-shifting kaleidoscope of colors that reflect the emotions of the individual passing through it. The colors will coalesce into shapes or landscapes, but determining what is real and what is illusion requires a wizard with the keenest mystic senses.
Raggadorr - For centuries Raggadorr was thought to be as far as a mortal wizard could travel without sleeping, dying or undergoing some form of mystic transformation, but then a treacherous passage was found through the Winding Way that opened up the Archipelago.
Though the realm appears to be ruled by the entity also known as Raggadorr, the rings themselves may be sentient. Agamotto freed the fourth Ring of Raggadorr from the Dungeons of Dyzakk during his travels across the dimensions.
The SPLINTER REALMS (The Dark Dimension, the Archipelago of Anguish and Redemption) - Once a single massive plane, the Splinter Realms were shattered long ago into many planes during a conflict. Earth's physical laws often do not apply. Islands float into the ether and are consumed by surreal gaping jaws. There is no gravity as we know it. Time moves in different ways. The Splinter Realms are ruled by a myriad of warring mystic entities who seek to expand their territories. In rare situations the Lords of the Splinter Realms can be called together, such as during the battle with the "Archenemy." Many of Earth's underworlds are connected to the Splinter Realms and there seems to be a connection between the Dark Dimensions and the darker aspects of existence (death, fear, confusion).
The Winding Way - The Winding Way is many things, a gateway to reach the Dark Dimensions, a source for immense mystic power and a living entity. Supplicants of the Winding Way use a technique that combines ecocentric and exocentric magic to draw power from this sentient plane. Usually exocentric magic involves the spell-caster's following certain prescribed procedures for the invoking and petitioning of extradimensional entities. In the case of the Winding Way, the dimension is the entity. And the entity seems to be making up the rules as you go along. The Winding Way once made the sorceress Margali Szardos so powerful that she was able to create a fully functioning replica of Dante's Inferno and then a short time later left her barely able to read signs from a cup of tea leaves. Woven throughout the Winding Way, the Tapestry Islands are home to the Weaver Witches and their ruler Viliven. Enitharmon the Weaver is said to live on one of the Tapestry Islands. A path of stones and gnarled roots leads from the Tapestry Islands to Nornheim, the home of the three Norns/Fates.
The Citadels of Sephiroth - The denizens of this Dimension are descended from the Winged Lords of Akah Ma'at, a race created by the Elder Goddess Oshtur to balance the creations of her brothers. Set had his Serpent Men and Chthon had his Wolfmen and Oshtur wished to create a race as noble as those other two were vile. Eventually there developed two distinct camps within Akah Ma'at; the righteous avengers of the Asura and the peaceful guardians of the Seraphim. Chthon took advantage of this schism and turned the factions against one another. The resulting war caused such destruction to the earth that Oshtur banished the whole city into the Dark Dimension. Stranded in this hostile environment, the warring factions made an uneasy peace that exists even today. Together they forged the Citadels of Sephiroth. These citadels serve as a line of defense against creatures from the Dark Dimension that would invade the Lower Realms.
Dyzakk - Called the "Dungeon Dimension" by many of those forced to spend time there, The Plane of Dyzakk is an enormous prison for any sorcerers, witches, demons, devils and angels who have been found guilty for crimes against the mystic principalities of the Octessence. Dyzakk created the dimension in the 24th hour of the eighth day of the week making it very difficult to reach.
Krakkan - If Dyzakk is the "Dungeon Dimension" then Krakken may be said to be a torture chamber. The two dimensions frequently work together to punish and restrain those who have offended the Octessence. Known across the dimensions for the unbreakable Chains of Krakkan this dimension bears the name of the entity who rules it. The Splinter Realm ruled by Malevolence, the King of Pain, is intertwined with the realm of Krakkan.
Farallah - Beyond Krakkan is the brutal dimension of Farallah, where fang and fist rule in an "eat or be eaten" environment. Brutus Klor and the Murder Clans are servants of Farallah and reside in an adjacent realm.
The Veils of Valtorr - The Dimension of Valtorr is a gloomy place of vapor and decay. This dimension is ruled by the smoky, serpentine entity Valtorr. The High Seers of Nox who reside in a pocket dimension are the vassals of Valtorr. They gaze into Valtorr's noxious vapors and see possible futures.
Watoomb - The Vapors of Valtorr are blown aside by the fierce swirling winds of Watoomb. The ruler of this stormy dimension was once a mortal sorcerer who achieved the remarkable feat of conquering one of the Splinter Realms and claiming it for his own. The Boreas Dimension where icy Ikthalon dwells is linked to the Plane of Watoomb.
Balthakk - At the edges of Watoomb the storms grow ever fiercer until everything seems to crackle with lightning and energy. Balthakk is a plane of pure destruction which is ruled by Balthakk, a being of living energy.
Otherplace (limbo) - A plane populated by demons where time moves in a very different manner, Otherplace has been ruled by various demons and sorcerers including Belasco, Illyana Rasputin, S'ym, N'astirh, Amanda Sefton and Witchfire.
The Dark Dimension - When the original massive dimension was shattered the largest remaining piece became known as the Dark Dimension. As the largest and most aggressive dimension it has successfully conquered and assimilated many of the smaller splinter realms into itself, making it a synthesis of realities merged by mystic means into a single domain. This process of merging realities came to a temporary stop when the realm of the Mindless Ones was joined to the Dark Dimension.
Rodann (Kingdom of Tazza) - During Dr. Strange's quest to rescue Clea from the nether dimension to which Dormammu had banished her, he was lured to the twilight kingdom of Tazza, a land ruled by a paranoiac lord who delighted in stealing the souls of heroes who visited his realm and keeping their immobile bodies on display.
Shazana's Realm - Mystic realm is ruled by the usurper Shazana, who toppled her half-sister and seized control. Dr. Strange briefly set matters to right there, but Shazana again gained power and rules her realm to this day.
Halls of Fear - Realm of the Dweller in Darkness, the embodiment of man's collective fear.
Realm of Madness - Beyond the Nightmare World in the Dream Dimension lies the Realm of Madness, where one's greatest fears take on a tangible form. The Realm of Madness lies in some sense beyond the Dream Dimension, but can also be reached directly.
The Dream Dimension - Literally a manifestation of the collective psyche of mankind. The Dream Dimension is connected to the Mindscape, which is in turn connected to the Astral Plane. The relationship between these three realms is similar to the relationship between the id, the ego and the super-ego. The Dream Dimension straddles the line between the Splinter Realms and the Far Realms. The Dark Dimension side of the Dreamscape is a twisted place of shadow and fear, ruled by the malicious entity known as Nightmare.
The FAR REALMS or The Celestial Concordance - The Far Realms are more the idea of a place than a place, composed of concepts and consciousness rather than things and people. The physical world has been utterly stripped away by passing through the destruction and death of the Dark Dimensions and the higher consciousness that remains may travel into the Far Realms. Little is known about these planes as very few have ever visited them.
Munnipor (Moons of Munnipor) - Ruling from their lunar mansions on the many Moons of Munnipor, the manifestations of Munnipor (maiden, mother, beldam) bestow understanding to supplicants and travelers.
Cinnibus (Suns of Cinnibus) - The Seven Suns of Cinnibus never set and continuously burn with the mystic light of wisdom. This dimension of peace and enlightenment is ruled by the Seven Sons of Cinnibus.
The Well Beyond the Worlds - A fabled place linked to the very core of magic.