The Dreaded One

If the powerful Dormammu’s exact beginning has ever been recorded on Earth, it was either lost or remains undiscovered. But, suffice to say, the powerful being has ruled his native Dark Dimension for untold ages and is its complete master. Despite his dominion over his home, the evil entity still craves more power and has decided that only by conquering and subjugating all other realms, planes, and dimensions can he ever truly be sated in his desires.

For reasons purely his own, Dormammu has set his eye on Earth’s plane as the most important to conquer, perhaps owing to its suffusion of magic and magic-wielders. At some point in Earth’s past, a tome—the Book of Cagliostro—was crafted to include a ritual to summon Dormammu, providing the means for humans to approach the powerful being and form a connection between Earth and the Dark Dimension. This is important because the presence of three magic Sanctums on the planet prevent Dormammu from invading himself, despite his immense abilities.

Power has its Limits

In the timeless Dark Dimension, Dormammu reigns supreme and wields forces beyond human comprehension, but he can be impacted by powerful artifacts such as the Infinity Stones, even to the point of cowing him and halting his actions.

In addition, the entity can grant a portion of his power to humans and other lesser beings for the purposes of extending their mortal lives and a certain degree of magical proficiency. The exact cost of these gifts from Dormammu varies, but can range from physical disfigurements to deeper disabilities.

Dormammu's fight with Doctor Strange (Stephen Strange)

Battling the Dark

Earth’s Masters of the Mystic Arts oppose Dormammu and his desire to merge the planet with the Dark Dimension, though the lure of power is always present. In fact, The Ancient One, one of Earth’s Sorcerers Supreme, secretly leached dark energies from Dormammu to prolong her own life and later argued that to do so bent evil to serving good’s goals.

The newest of Dormammu’s enemies and perhaps destined to be one of his greatest, is Doctor Stephen Strange, a student of The Ancient One and wielder of the Eye of Agamotto, a powerful relic with the power to halt the Dark Dimension’s ruler in his tracks.

Dread Acolytes

One of the most successful, to a point, of Dormammu’s terran allies was Kaecilius, a man who sought to end death’s hold on humans. Kaecilius, assisted by other magic-wielders who shared his beliefs, used the Book of Cagliostro’s ritual to open a channel to the Destroyer of Worlds to this end, but ultimately (and unwittingly) sacrificed himself and his Zealot followers to Dormammu’s disappointment in defeat.

Strange Days

After the death of his family on Earth, Kaecilius drew power from Dormammu to lend strength to his plan to allow the Dark Dimension to overlap and subjugate the planet, thus ending humans’ mortal limitations. When Stephen Strange became a student at the temple of Kamar-Taj, which was once Kaecilius’ own place of learning, he heard of the man’s treachery and eventually set himself in opposition to his evil goal.

Several battles between the Zealots and Strange ensued over not only Earth’s reality, but also other planes, resulting in the death of The Ancient One and nearly the loss of the entire planet and its plane of existence to the Dark Dimension and its ruler. In the end, Doctor Strange had absorbed enough knowledge of magic and its wielding to make his way to Dormammu’s dimension and confront him with a time-loop constructed with the Eye of Agamotto. The artifact and Strange’s clever trap convinced Dormammu to release Earth from his grip and agree to end his march to conquer it.

Disappointed and disturbed by his defeat, he completed his corruption of Kaecilius and his followers by transforming them into beastlike creatures and bringing them over to the Dark Dimension for all eternity. It is presumed that as long as Doctor Strange keeps watch on Earth, the Destroyer of Worlds is prevented from ever launching another such mystical assault.