BIOGRAPHY
The full origins of the man known as Maha Yogi are unknown. He was born circa 8,250 B.C. in the region that would eventually become Scandinavia. Under unrevealed circumstances, he developed psychic powers, including telepathy, telekinesis and teleportation. The man has frequently claimed to be a mutant, but other sources state he was mutated by the Caretakers of Arcturus. [Doctor Strange, Sorcerer Supreme #27]
This man was also present when one of his tribesmen encountered an alien and destroyed the mystical crystal circuit known as the Hellfire Helix. A fragment of the crystal embedded in the 
tribesman’s chest as it was destroyed, granting him immortality as the hunter eventually known as Ulysses Bloodstone. The future Maha Yogi also scavenged one of the crystal shards, making it his Jewel of Jeopardy. The mutant found that he could enhance his psychic powers with the jewel, and that it also kept him forever young. He moved throughout history in different guises, bearing witness to the rise of the pyramids and the death of Caesar, among other moments. [Marvel Presents #1, Incredible Hulk (2nd series) #210]
At one point, he secretly replaced the magician Merlin in Camelot at King Arthur’s side. He used his mental powers to fool others into believing he had the same magic as Merlin. A full account of the Mad Merlin’s activities in that role is incomplete, but he was captured once by the time-traveling Kang the Conqueror and also became rivals with the mystic known as Modred. [Strange Tales (1st series) #134, Marvel Chillers #1] Sersi of the Eternals once claimed she taught Merlin a few minor tricks, and she was apparently instrumental in helping the real Merlin overcome his doppelganger and seal him away in suspended animation for centuries. [Eternals (1st series) #4, Incredible Hulk (2nd series) #210]
[Note: The role of Merlin in Marvel Comics is a long and contradictory one. The Mad Merlin was the first version to appear in the Silver Age, and initially Marvel ran with the “Merlin was an evil mutant the whole time” idea. After Black Knight and Captain Britain stories, though, they affirmed that Mad Merlin was a separate character from Camelot’s Merlin. At one point, Marvel suggested there were three Merlins: Arthur’s Merlin, the Maha Yogi, and Merlyn of Otherworld who ALSO posed as Camelot’s Merlin at times. Merlyn once even claimed Mad Merlin as one of his many identities, further obscuring the issue. Presently, it is accepted that Merlyn of Otherworld and the Merlin of Camelot are the same being, that he acts inconsistently at times to manipulate others or because different aspects of his persona are ascendant, and that Merlyn only claimed to be Mad Merlin to impersonate his own imposter and throw doubt on his agendas.]
In modern times, the tomb of Merlin was discovered and put on display at the New York Museum. 
Once the tomb was opened, the spell which trapped him there ended and the Mad Merlin escaped reacquaint himself with society. Seeking to become “the power behind the power” as he had been in Camelot, the Mad Merlin plotted to interrupt the U.S. Space Program, and then fix his sabotage once the government recognized the value of his “magic.” When he telekinetically sent a rocket off-course, however, the problem was quickly fixed by the Mighty Thor.
Merlin realized he would have to deal with the Thunder God before others would fear his might. Merlin teleported into the White House and announced his intentions to challenge Thor to a duel of powers. Thor responded to the news flash and began jousting with the Mad Merlin. The “wizard” could hypnotically paralyze the Thunder God or animate landmarks like the Lincoln 
Memorial, the Washington Monument or even the Pentagon to crush Thor. The Avenger countered each attack but had to think quickly to outwit Merlin for good. He made a risky play to transform back into Donald Blake, and bluffed Merlin into thinking this was just one of many countless forms Thor could magically assume and attack him with. The paranoid conjurer believed he was outmatched and submitted to Thor as the winner of their contest. Thor commanded Merlin to return to his crypt and sleep for another thousand years, and the man meekly complied. [Journey into Mystery (1st series) #96]
Merlin’s self-imposed suspended animation didn’t last, however. Although his body was dormant, his mind remained active as it remotely explored the modern age. He monitored Thor’s activities until it was safe to emerge again, while mentally gathering mercenaries and other forces to serve him. In his new identity as the Warlock, he had an entire Medieval castle built in a subterranean cavern, his men armed with advanced weapons, and construction begun on a massive apparatus. Using his mental power and the technology of the modern age, the Warlock would turn back the mental development of civilization by a millennia. With all modern science and knowledge lost to superstition, he and his private army would rule.
During his preparations, however, the Warlock detected a mind which might be able to resist his schemes, Professor Xavier of the X-Men. Using the element of surprise, the Warlock teleported 
Xavier and his protégé Marvel Girl into his presence, leaving the other X-Men trapped in the null space between the two points when they tried to follow. By taking them off-guard, the Warlock was able to place psychic blocks in Xavier’s mind to inhibit his powers, and enthrall Jean Grey into submitting to his will without question. Still, Xavier was not completely helpless. He pretended to have no power to oppose the Warlock, while secretly marshalling his strength. While the Warlock was focused on Marvel Girl, Xavier reached out and summoned his lost X-Men from the void where the Warlock left them.
Although the X-Men had reinforcements, they still faced a man with centuries of experience with his psychic powers. The over-confident Warlock forced the male X-Men into a faux tournament against his mercenary knights. He even wagered with the professor that, if his men lost, he would give up his plans and return to suspended animation. The X-Men won against horsemen, laser lances and hidden snipers, but the Warlock did not accept defeat gracefully. He attempted to flee with the mesmerized Marvel Girl, while holding off his attackers at the rear. By splitting his concentration so much, however, the Warlock lost his grasp on Xavier and Jean’s minds, returning their powers and their senses fully. He could not focus on so many opponents at once, and soon was overwhelmed. As the X-Men occupied him physically, Professor X targeted his mind and forced the Warlock back into suspended animation. [X-Men (1st series) #30]
The Warlock would not rest for long, though, and he soon resurfaced in Greenwich Village disguised as a stage magician called the Maha Yogi. The climax of his act was an unexpected 
session in mesmerism. Each audience he performed for were left with powerful post-hypnotic conditioning to rise up as his slave army when the time was right. However, the Beast and Iceman recognized their old foe while attending his show and interrupted the act. The Maha Yogi pitted his hypnotic illusions against two minds trained to resist psychic attacks. Eventually, the Maha Yogi’s concentration was broken again, this time by the theatre’s light & sound display. He lost his control over the audiences and fled the cacophony into the arms of the waiting authorities. [X-Men (1st series) #47]
The Maha Yogi went into seclusion, rebuilding his army of mercenaries for future schemes at a renovated castle in New Jersey disguised as “Merlin Industries.” He also acquired a powerful bodyguard, the extra-dimensional warrior called Mongu, by rescuing him from his descent through 
the Abyss of Eternity. Maha Yogi studied the power of the Hellfire Helix found in his Jewel of Jeopardy, in the hopes of using it to fuel a scheme for world conquest. His plotting was detected by Doctor Druid, who recruited Bruce Banner as his ally to seek out and stop the Maha Yogi. The Mad Merlin detected their attempt at infiltrating Merlin Industries and turned his mercenaries against the spies. When Banner became the Hulk, Druid subtly used his psychic powers to coax the brute alone as his protector. Maha Yogi felt these psychic emanations and attempted to control the Hulk himself. The conflicting mental commands overwhelmed the Hulk’s mind, knocking him out and leaving Doctor Druid as an easy target for capture.
The Maha Yogi’s affection for tournaments remained, and he thought to pit Hulk against Mongu for sport in the arena while he continued studying his gem. When the Hulk proved to be stronger than the warrior on equal grounds, the Maha Yogi called upon the Jewel of Jeopardy to augment Mongu’s power. As before, splitting his focus caused the psychic to lose his concentration on keeping Druid entranced. Doctor Druid psychokinetically wrested the Jewel from Maha Yogi’s grasp, tossing it into the arena. The Hulk found the Jewel annoying and crushed it, causing the Maha Yogi to lose his eternal youth. The effects of centuries delayed quickly overcame the mentalist. Mongu remained loyal to the Maha Yogi and left in peace to care for his now-wizened master. [Incredible Hulk (2nd series) #210-211]
[Note: The importance of the Jewel of Jeopardy came out of nowhere. The Maha Yogi had not noticeably relied upon a jewel in any of his previous appearances. In X-Men #47 he did carry a “Jewel of Jeopardy” but it was just a rock that he chucked at Iceman as a weapon of last resort… hardly the precious and life-sustaining item it appeared as here.]
Somehow, the Maha Yogi reclaimed his vitality. He became part of a convocation of wizards called Eternal Youth, who sought artifacts of immortality and power for their own ends. They were supposedly founded by the Maha Yogi’s one-time foe Doctor Druid, who was later at odds with the group. Maha Yogi and Mongu attacked Avengers Mansion with le Sabre and Chondu the Alchemist while seeking Druid, unaware that he had left the group. They were beaten in a scuffle with Black Widow and Crystal. [Avengers Annual #22]
Operating on his own again, “Merlin Demonspawn” learned the Holy Grail was held in the horde of a dragon who once fought the epic hero, Beowulf. Grendel and Grendel’s Mother fought Beowulf before the dragon, and Merlin believed they knew the location of the horde. Grendel’s Mother was imprisoned in a magical orb that made its way from Scandinavia to America as continents shifted over the centuries. Merlin believed he could free her through magic, but it would require a sacrifice of a hundred virgins’ blood at a particular time and location, which turned out to be Los Angeles on a weekend. In order to acquire his sacrifices, Merlin built a comic book store on the spot where his spell must be cast.
Over a period of weeks, “Comic Book Castle” had a grand opening and a series of lavish sales to garner attention. Merlin hoped to build up to a major event on the night he needed to cast his spell. His efforts at being discreet were not wholly successful, however. Merlin previously played with the mind of Red Raven, a hero who tracked him to the Castle. With a bit of transmogrification, 
he changed Red Raven into his namesake and avoided further conflict. However, Comic Book Castle also began siphoning customers from Golden Orange Comics nearby, run by Marlo Chandler. Marlo was married to Rick Jones, who in turn was molecularly bonded to Captain Marvel, meaning even more super-heroes were orbiting around Merlin’s scheme. [Captain Marvel 4th series] #9-16]
When the necessary alignment came, Comic Book Castle’s big giveaway attracted all the sacrifices Merlin could want. A small drug in the party’s punch meant the victims willingly cut their hands to release the virgin blood he needed to release Grendel’s Mother. Merlin’s plans soon unraveled, though, for Grendel’s Mother refused to aid him merely because he arranged her freedom. Marlo Chandler was scouting her competition when the sacrifice occurred, and her 
presence drew Captain Marvel and Moondragon to the rescue. Merlin turned his spells against the heroes until Rick Jones suggested they reflect his power back on him. With the Nega Bands as a mirror, Captain Marvel turned Merlin’s final spell against him, and Merlin Demonspawn, the Warlock, the Maha Yogi, wound up trapped in the same prison from which he had released Grendel Mother’s. [Captain Marvel 4th series] #20-21]