There are many other dimensions in what is known as the universe. Many of these are home to entities that are called upon for mystic power: the Crimson Cosmos of Cytorrak, the Twelve Moons of Munnipor, the Purple Dimension, and the Veils of Valtorr, to name a few. Most feared among these by the denizens of the mystic realms is the Dark Dimension of the Dread Dormammu, one of a number of dimensions known as the Splinter Realms. Dormammu is not the original ruler, but he has claimed to rule it for a hundred thousand Earth years to date.
According to legend, the many netherworlds currently known as the Splinter Realms were once one dimension. Due to ancient mystic conflicts, the dimension was shattered; the largest of these splintered realms soon became known as the Dark Dimension. For a long time, the Dark Dimension was a fairly peaceful realm, whose near-human people were ruled by a cabal of sorcerers known as Mhuruuks. The leader of the Mhuruuks and hereditary ruler of the dimension was an ambitious man known as Olnar, who sought to return to wars of conquest. However, Olnar had already conquered all of the Dark Dimension, and expanding into the other Splinter Realms was proving difficult.
That is when Olnar was visited by two Faltinians: Dormammu and Umar, siblings who claimed to be fleeing persecution by the rest of the Faltine and had taken on forms of matter rather than energy in order to hide. (In truth, the two were exiled for unspecified crimes against another Faltinian.) Dormammu showed Olnar how to merge other Splinter Realms into the Dark Dimension in order to facilitate their conquest. Secretly, however, Dormammu and Umar plotted to take the throne themselves. At Umar's urging, Olnar connected the Dark Dimension to another of the Splinter Realms, only to be immediately killed by that realms' denizens, the Mindless Ones, a nearly indestructible race who only sought the destruction of every living being – including each other, when no other targets presented themselves. Dormammu changed back into his Faltinian energy form in order to fight back the Mindless Ones and seal them behind a mystic barrier; Umar refused to return to energy state and as a result was severely weakened. The people of the Dark Dimension hailed Dormammu and Umar as saviors; riding on this wave of popularity, Dormammu named himself regent of the Dark Dimension until such time as Olnar's infant son, Orini, was able to take over.
Dormammu, however, had no plans to relinquish the throne, nor to face any other possible claimants to the throne. Orini was raised to become Dormammu's high priest and loyal disciple, while Umar was banished to a far corner of the dimension. Dormammu would send people to Umar to make sure she wouldn't escape or plot against him. After Orini achieved adulthood, he was sent to oversee Umar for a year. Neither Umar nor Orini said what happened, but Orini returned with an infant girl in his hands, who he named Clea and claimed he had adopted to raise as his own daughter. Although Dormammu suspected the child was the daughter of Orini and Umar, he could not be certain, and never again sent Orini to meet with Umar.
Dormammu has long sought to break down the barriers between Earth (which many of the Netherworlds call "Eden") and the Dark Dimension. This has brought him into conflict with Earth's Sorcerer Supreme and other mystics throughout the ages. Most of these conflicts are undocumented; it is possible he has only recently learned of Earth, though it is equally possible that other conflicts – presumably with other mystic principalities – has kept his attention away from Earth for long periods of time. It is known that in the early 20th Century the Sorcerer Supreme known as the Ancient One defeated and humiliated Dormammu, leading to Dormammu's hatred of the Ancient One and those the Ancient One taught. This enmity has extended to the Ancient One's successor and the current Sorcerer Supreme, Doctor Stephen Strange.
Doctor Strange has visited the Dark Dimension on two known occasions; both times he ended up facing off against Dormammu. On the second occasion, Clea secretly weakened the barrier keeping the Mindless Ones contained; which led to Strange aiding Dormammu in repairing the barrier. (Clea was later banished from the Dark Dimension to Earth as a result.)
Dormammu was recently ousted from rulership of the Dark Dimension by Umar under unrevealed circumstances. Umar is said to be far more cunning, manipulative, and imaginative – and equally as ambitious – as her brother. What this means for the Dark Dimension and Earth in the long term has yet to come to light.
The people of the Dark Dimension age at a greatly reduced rate compared to people of Earth. Whether this is an attribute of the Dark Dimension (and mystic realms in particular) or an attribute of the people themselves is unknown.
Space in the Dark Dimension is multi-faceted, working on four or greater spatial dimensions. It is possible to enter a doorway or other portal and wind up in an entirely different portion of the plane, and gravity is often subjective; there are places in the Dark Dimension that greatly resemble something out of an Escher painting.
It should be noted that the Netherworlds ruled by mystic principalities such as Cyttorak, Dormammu, and Raggador are separate from the various Hell dimensions ruled by Earth-spawned demons such as Mephisto, Satannish, Chthon, and Set, as well as from deific realms such as Avalon, Olympus, and Asgard.
First Post-Reboot Appearance: DOCTOR STRANGE: SORCERER SUPREME #
The Dark Dimension is in a very interesting place, technologically speaking. In some ways it is a low-tech society, with most technology used by the denizens in the TL 1 to TL 3 range, but the high degree of magic makes broadcasting holographic images with sound plane-wide a literal snap. Treat the Dark Dimension as TL 3+4^ or TL 3+5^ – effectively TL7 or TL8 with a TL3 veneer using magic "superscience". Most denizens live in simple dwellings which lack most modern amenities. For things such as effective Starting Wealth and monthly incomes, treat the Dark Dimension as being TL5 ($5,000 for Starting Wealth and $1,100 per month, before Wealth level modifiers).
The Dark Dimension is considered a very high mana area/place of power for casting. This means that FP/ER spent on egocentric magic – or for contacting entities for exocentric magic – is recovered at the start of the mage's next turn, and the threshold for working ecocentric magic is doubled. In addition, the recovery rate for ecocentric magic is also doubled. On the other hand, failures are automatically critical failures, and fail spectacularly, all ecocentric failures rolled on the Critical Spell Failure Table (GURPS Magic, p. 7) reroll on a 9 to 12, and ecocentric failures roll on the Calamity table (GURPS Thaumatology, pp. 77-78), adding 10 to the roll.
The Mhuruuks and other humanoid denizens of the Dark Dimension are effectively human, with the added ability to change their skin, eye, and hair colors at whim (at best, this is a Perk, though here this ability is treated as a 0-point Feature since it's like changing one's hair style or clothing). There are other denizens who do not fit the traditional humanoid frame, but all are potentially adept at magic. Most denizens only have Magery 2 [25] (price includes Magery 0) and points in the Energy, Matter, and Space Realms without exceeding skill 15.