Baron Karl Amadeus Mordo is an accomplished master of the mystic arts, particularly the dark arts, having trained under German mystic Viscount Krowler and the Ancient One, Earth’s Sorcerer Supreme. Despite being one of the most powerful sorcerers in the realm, the Ancient One picks another sorcerer as his chosen disciple, Doctor Stephen Strange, AKA Doctor Strange. Mordo remains as Strange’s fellow student, but his ego takes hold, and he eventually leaves to amass more power and slay both Strange and the Ancient One. Mordo works with the sorcerer-tyrant Dormammu and employees several mystics to support his feud with Strange, which continues into the modern era.
In the wake of World War One, Nikolai, the first Baron of Mordo in the Transylvanian village of Varf Mandra, ordered Miarka, Queen of the Gypsies, to teach him enough magic so that he could restore his homeland to its former glory. Looking to do the same for Germany, Viscount Heinrich Krowler knew he needed more spells on his side, so he ordered his daughter, Sara, to marry Nikolai. She succeeded in her mission and gave birth to a baby by the name of Karl Amadeus Mordo shortly after. The Viscount had cast a spell of transference on the boy that would allow the grandfather to learn all of the magical secrets the boy absorbed.
Karl grew up a lonely child in an old castle where his mother didn't care for him, and his father was too wrapped up in his pursuit of the dark arts. When Nikolai got too close to his own goals, Sara killed him. She took more of an interest in her son and decided to move back in with her father. Under the Viscount's tutelage, Young Karl became fascinated with the dark arts and took to them quite well. However, upon secretly hearing that they'd had his father killed, Karl swore vengeance against his mother and grandfather.
Just as World War II erupted—thanks to the Viscount and his friends throwing their money and power behind Adolf Hitler—Krowler sent Karl to find the Ancient One and learn all he could from him. Incorrectly thinking he'd fooled the teacher, Mordo still worked towards killing his mother and grandfather, which he did, dedicating their suffering to the Dread One, AKA Dormammu.
Strange New Worlds
Mordo had already begun his studies with the Ancient One when the American Doctor Stephen Strange appeared seeking a cure for his severely damaged hands. However, even before that, upon hearing that he was not the actual Chosen One, Mordo began haunting Stephen in an attempt to keep him away from the Ancient One's path.
Though initially not interested in learning the ways of magic, Strange stayed on because of a storm created by the Master. Mordo did not care at first, as he had thrown himself into his studies. However, Karl considered his teacher more of a threat than anything and allied himself with Dormommu to kill the Ancient One. When Strange stumbled upon these plans, Mordo used his powers to make it so the newcomer could neither speak nor act against him. The plan backfired when Stephen decided to dedicate himself to studying magic to keep the Baron from killing their teacher, inadvertently creating his own mystical foe in the process.
Eventually fed up with Strange's superior grasp of the mystic arts, Mordo left the Ancient One's Himalayan refuge, an act that restarted the aging process which had been suspended during his studies. He eventually returned to Varf Mandra and became a feared ruler. While researching his family history, he discovered his father's affair with Miarka and the secret daughter she bore him, Lilia. Now a woman, Lilia had become the new Queen of the Gypsies and inherited the Book of Cagliostro, which her own daughter, also named Lilia, kept hidden.
Feigning romantic interest in the second Lilia, Mordo found and stole the book. He thought he killed her in the attack and fled. Lilia would eventually return to torment him, but this pursuit gave Mordo even more dark knowledge to use against his foes.
Obsessed With Strange
While Strange still studied under the Ancient One, Mordo appeared and offered him a healing elixir that would fix his hands once and for all. However, Stephen refused, solidifying him on his path to becoming the Sorcerer Supreme.
In his effort to become the most powerful black magician, he intended to kill the Ancient One by using astral projection to trick his own servant into poisoning the master. The teacher refused to convey his dark secrets to the wayward student, but Doctor Strange appeared and wound up tricking Karl’s astral form into returning to his physical body.
Other schemes included trapping Strange in London and enchanting the Ancient One in the Crimson Circle of Cyttorak. However, Strange proved the better thinker and magician time after time, though Mordo always exhibited a great deal of magical power.
He crossed a line when he made a deal with Dormammu. With Dormammu’s support he managed to knock the Ancient One out, but Strange escaped with their master. To find him, Karl put out a call to his fellow evil sorcerers to track Strange down. On the run, Strange eventually faced Mordo and Dormammu—with an incredible power upgrade thanks to the Dread One—nearly succeeded in killing their shared enemy. However, Stephen teleported himself to another dimension with the last of his power.
Backed by Dormammu, Mordo fought Strange to a standstill until, fed up with the Baron's inability to defeat his opponent, the Dread one cast a spell that brought all three Earthlings to him in another dimension where Dormammu fought Strange. When it looked like the human would win, Mordo blasted him in the back with a spell!
Instead of pleasing his ally, though, Mordo only managed to shift Dormammu's wrath from Strange to himself. In a rage, Dormammu banished Mordo to the Dimension of Demons. While he was gone, Mordo's minions still troubled Doctor Strange. However, Strange brought Baron Mordo back to his home dimension after rescuing other victims of Dormammu. Though freed from the demon dimension, Mordo found himself jailed by The Ancient One.
Upon escaping, Mordo continued to watch for his nemesis through his various agents out in the world. He found out about Strange's quest to find Eternity and attempted to stop him more than once, failing every time. However, while Strange communed with Eternity, Mordo kidnapped The Ancient One and held him captive.
Menacing Partners & Minions
Baron Mordo led several mystics in his employ and had them stationed across the Earth. Although each of his followers possessed some affinity for magic, none was as adept as Mordo himself. Mordo’s minions included Sir Anthony Baskerville, an old ally of his grandfather who had come to Mordo in the hope of having his severed right hand restored to his body. The ranks of his followers increased after allying with Dormammu, Lord of the Dark Dimension, and include the sorcerer Demon, AKA Demonicus, his chief disciple Kaecilius, and Adria who becomes his deputy leader. Mordo often employs his minions to distract or capture his foe Doctor Strange. But even his partners against Strange, like Dormammu, prove unreliable.
Schemes Throughout The Eons
Not long after, Doctor Strange defeated Zom, accidentally awakening dark powers in the minds of many mystics—which allowed Mordo's escape from his prison. Enraged at his rival's recent acquisition of The Ancient One's powers, Karl attacked, ignoring Strange's pleas for help to stop the coming of The Living Tribunal. With a great deal of prodding from Strange, Mordo agreed to allow his foe to exorcise all of the evil occult energy and place it inside himself.
With all that power coursing through him, Mordo rashly attacked Strange instead of aiding him further to stop the Living Tribunal's arrival. Though Karl amassed more power by the time Doctor Strange returned, he could not stand up to his foe's power and soon found himself banished once again.
Baron Mordo eventually found a way to return and even took over Doctor Strange's identity when the hero wore a mask. However, the real deal returned and bested his foe, re-dedicating himself to mastering the mystic arts once again. Mordo then jumped through time, first to Paris in the 18th century to claim the Book of Cogliostro and then to the beginning of time itself with Doctor Strange and Sise-Neg, but Karl soon had a breakdown after seeing the face of God that put him in Strange's care for a year. He remained in the Sanctum Sanctorum in silence. While Stephen met with Eternity, Mordo ran from his room and escaped, eventually arriving at the home of the Aged Genghis.
Mordo kept a relatively low profile for a while, but eventually returned to send Strange's one-time friend Lord Julian Phyffe against him, followed soon by Man-Thing who he had manipulated for his own purpose. Using Man-Thing ended up throwing him into interdimensional exile, but he returned in the 1940s to torment Strange with some help from Dormammu. At that point, Strange used Mordo's power to stop a Dormammu-possessed Viscount Krowler.
After that defeat, Mordo spent years planning his next attack on Strange, which came as a complete shock to the Master of the Mystic Arts. He had gained increased power because he sold his soul to both Satannish and Mephisto. The Baron knew that they would both come to collect and that a mighty battle would ensue, so he trapped himself in a contained space with Strange's ally Sara Wolfe, essentially forcing Stephen to help him fend off the two debt collectors. Mordo hoped that, after facing both demons, he could step in and quickly finish Strange off.
Strange did his best, but Satannish came for his debt, taking both Mordo and Wolfe back to his dimension. Eventually, Mephisto also appeared, and the demonic duo fell into a battle that wreaked havoc across dimensions. Ultimately, Mordo felt some humanity bubble up inside him and sent Sara Wolfe away from the danger just before Strange figured out a way to get both demons to take away from his soul.
Better To Rule In Hell
Since extradimensional exile had proven so unreliable, Strange imprisoned Mordo in his Sanctum instead, but over the weeks following, Mordo slowly won the sympathy of Strange’s associate Wolfe. Not long after, during a time when Strange struggled with Dormammu, who had been deposed by Strange’s disciple Clea, Mordo managed to trick Wolfe into releasing him. He immediately imprisoned her and took control of the Sanctum Sanctorum. When the Dread One attacked the Earthly plane, Mordo fought against him, even refusing the demon's offer of working for him. The pair fought again, but when Mordo lost, he decided to take Dormammu's offer anyway, thus making him the ruler of the Earth-dimension albeit as his vassal. Secretly, however, he joined forces with Dormammu’s twin sister Umar the Unrelenting. Umar offered Dormammu a piece of the Dark Dimension to rule and then claimed the rest for herself and Mordo, who would be her consort.
After Clea later dethroned Umar and Mordo, the Baron eventually made his way back to Earth, where he realized that he was dying. He revealed not only this truth to his longtime enemy, but also how he'd sent demons after him in the past and blocked his memories. When the two connected mentally, Mordo passed his terminal cancer on to Stephen. Around this same time, Karl's daughter Astrid took over Mordo Castle and used the dark arts to bring Strange there. While both captive, Karl wanted to atone for all the terrible things he did before dying, and does so by taking the cancer back into himself.
Though he did not think he could take out his child, Mordo instead severed her soul from her body. He then died, his soul taken to the next plane by none other than the Ancient One.
A Time And A Place For Everything
Further down the line, Grandmaster and The Collector decided to set up another one of their contests. Grandmaster's champion Hulk chose to fight alongside Silver Surfer, Namor and Doctor Strange while Collector selected the original Red Hulk, Baron Mordo, Terrax and Tiger Shark, all from various points in history. Strange and Mordo fought on Silver Surfer's homeworld of Zenn-La before Galactus attacked, but was returned to his own time when Red Hulk ruined their game.
The Baron returned to the present thanks to "temporal shenanigans" and began tormenting X-Factor's Monet St. Croix, AKA M. He managed to drain her energy bit-by-bit to fight back the cancer that still raged through his body. Powered-up, we went to fight M's associate Guido Carosella, AKA Strong Guy, but they were ambushed by Mutant Response Division soldiers who shot Karl. Guido got them both to safety where he and Monet eventually made a deal wherein she would let him feed off of her until he cured his cancer as long as he got them out of the bunker they were in since it was about to be bombed. Mordo passed out after doing exactly that and, instead of healing him, M made him think she cured him before sending the villain on his way.
He suffered another setback when Ulik broke into his castle and stole an artifact that amplified his powers, which he used while working with Diablo, High Evolutionary and Crimson Dynamo against Thor and Iron Man. Though Mordo later appeared dead in a Brazilian temple with Thor's axe lodged in him, he showed up at the Bar With No Doors. He exhibited a great deal of magical ability even though everyone else's powers had diminished when the Empirikul attacked.
Soon after, he took over a family's apartment in Tribeca and showed up at the Sanctum to attack the far-less-powerful Strange. He was winning the battle but found himself without an opponent when Nightmare snatched Strange away. The whole while, he argued with Dormammu, who he had once again pledged himself to after the Dread One saved him from the Empirikul, preserving his control over magic.
When Dormammu grew impatient, he attacked Doctor Strange directly and burned Mordo when he tried claiming Stephen's life for himself. Angered, Karl added his power to Strange's so they could send the Dread One to his enemy Shuma-Gorath. When he then tried to destroy the significantly weakened Strange, though, Mordo wound up on the wrong end of a magical rope, the other of which was attached to the Phantom Eagle's ghost plane.
During the Secret Empire, in which a bastardized version of Captain America, Hydra Supreme, took over most of the world for Hydra, part of the villain's plan included putting a Darkforce dome around Manhattan. Mordo and HydraCap made a deal that placed the Baron in charge of the captives and set up shop in the Sanctum Sanctorum. In addition to keeping an eye on Strange, Spider-Woman, Ben Urich, and Kingpin as they amassed a magical cache, Mordo also trapped Daredevil and then went up against Luke Cage, Cloak and Iron Fist.
In the ensuing battle, Mordo became overconfident once again and, even though he had captured his opponents, he traveled too far away from the Sanctum Sanctorum. Using some classic illusionary trickery, Strange reclaimed his house and the others quickly put an end to Mordo's attempts at taking Manhattan.
Sometime after that, Mordo was freed and began working as an enforcer for Dormammu's race. In that capacity, he destroyed the demon Baroshtok, freed Strange's one-time apprentice Casey Kinmont, powered her up and sent her after the real Doctor Strange. Banished by Casey after Stephen helped her regain her soul, Mordo remains in the ether waiting to attack once more!