|Sources||Time Streams, Bloodlines, Rath and Storm, Mercadian Masques, Invasion, Planeshift, Apocalypse, Scourge, The Moons of Mirrodin, The Fifth Dawn, Planar Chaos, Scars of Mirrodin , Mirrodin Besieged , New Phyrexia|
Karn was a golem created as a probe by Urza and Barrin to enable their time traveling experiments.  His form was chosen because Urza's studies had shown that only silver could pass through temporal energies unharmed. In an effort to make the golem fully sentient, Urza included Xantcha's heartstone as part of his construction, allowing him to develop a personality which would grow and evolve and make decisions on his own should the need call for it.
 Tolarian Academy
After his activation, Urza entrusted the young Teferi, a student at the Tolarian Academy, to teach Karn about the world. Teferi saw him as an elaborate toy and endlessly harassed the golem, who knew no better. An example of Teferi's callous treatment showed in the name he chose for Karn, Arty Shovelhead. Disdaining Teferi's awful treatment of the being, a senior student named Jhoira took him from Teferi and began to teach him in earnest. She granted him the name Karn, a Thran word for "mighty." The experiments with Karn proceeded and an idyllic sort of life settled in, but then tragedy struck. When Jhoira's life was taken by a Phyrexian sleeper agent during an assault, Karn used Urza's time machine to go back and save her; though he succeeded, the time machine suffered catastrophic failure, destroying the first academy and leaving Tolaria a shattered temporal landscape.
Karn returned with Urza and Barrin to help rebuild Tolaria years later, and discovered Jhoira still alive, and Teferi trapped in a slow-time bubble. Jhoira and Karn worked hard and eventually devised a method to rescue Teferi. By that time, Karn had been sidelined by Urza, as the planeswalker had moved on to a variety of different projects. Karn was always present to serve, however, helping in the Mana Rig, even going so far as letting himself be used during the negotiations with the Viashino, and on the Skyship Weatherlight's first mission to Serra's Realm.
Eventually Jhoira left Tolaria, having chosen to remain in her native land of Shiv and run the mana rig with Teferi. Unfortunately, Karn missed her terribly, and fell deeper and deeper into a black depression which was slowly consuming him. In an effort to stem this problem, Karn frequently joined the Weatherlight voyages around the world, hoping the world at large would take his mind off his problems. It did not have the desired effect, instead just reminding him of all the things he was trying to avoid. Barrin showed deep concern for the golem's mental health and pleaded with Urza to try and find some way to help him. Urza acquiesced and placed a mental cap on Karn's memories, allowing him to recall only 20 years of his life at a time. There was only one thing that Karn never wished to forget, and every night he would hold a picture of Jhoira and repeat the mantra "Jhoira is my friend."
 The Legacy
Urza decided that the Weatherlight, Karn, and all the other artifacts he had built and collected over the years to further his quest against Phyrexia -- collectively, the Legacy -- needed a human component to wield them. He set about interfering with Dominarian bloodlines, trying to breed the perfect hero. The culmination of this project, the Capashen bloodline, was put under Karn's care.
The golem rescued young Gerrard Capashen from the Phyrexian raids on Benalia, and brought him to his adoptive father Sidar Kondo. When Kondo's son Vuel turned against his tribe and stole the Legacy, Karn went to retrieve it. During this effort, he was tricked into killing an innocent bystander, and was frozen by the Touchstone. He was later found and freed by Sisay, with the memory of killing the innocent fresh in his mind. Karn took a vow of pacifism, swearing never again to take a life.
During the Weatherlight's time on Rath, Karn was captured by Greven as he refused to fight off his attackers. He was taken to Volrath's Stronghold. There, he was tortured, being put into a room that would incessantly tumble, an endless supply of Moggs in it which he was forced to fall onto and crush until being rescued by Gerrard. As the Weatherlight crew fled the Stronghold, Karn knew he had a mission separate from the others, and went to seek the Legacy artifacts guarded by the Sliver Queen. By explaining to the hive-mind that the Legacy was part of him, Karn convinced the Sliver Queen to let him take the artifacts and depart in peace.
 Phyrexian Invasion
Early in the Phyrexian Invasion, while confronting Tsabo Tavoc in the caves of Koilos Karn realized his vow of pacifism kept him from protecting his friends and his homeworld. He was still torn by his desire to protect and his vow, but a strike upon his head broke the cap that Urza had placed upon his memories, and they came rushing back, most vividly of the Phyrexians he had killed to protect Jhoira. He was instrumental in helping Gerrard kill Tavoc and enjoyed the celebrations as much as any that night. The celebrations were to be short lived though, as the Overlay started the next morning. Despite his newfound willingness to kill, he spent much of his time in the Weatherlight's engine core, guiding the ship as it improved itself and further integrated the Legacy. Eventually, after the near destruction of the Weatherlight, Karn understood the entirety of the Thran Tome and with that knowledge, helped to trigger the Weatherlight's final evolution. Much to his surprise, he found he was no longer the only intelligence running the ship. To his joy, and despite the dire circumstances, Karn had finally found someone who could understand him completely. Alas, it was not to be, as Yawgmoth manifested upon Dominaria and the ship gave its life to try and slay Yawgmoth. Finally, as all hope of victory seemed lost, Karn united with Urza and Gerrard. When Gerrard placed Urza's powerstone eyes, the Mightstone and Weakstone, into Karn, the Legacy released a wave of white mana, destroying the Phyrexians and slaying Yawgmoth. While the two humans were killed, the powerstones turned Karn into the first -- and, so far as is known, only -- artificial planeswalker.
Karn later created Argentum, a plane of mathematical perfection. He sent probes to monitor Dominaria, but one of them was flawed and became the Mirari. Looking out upon the worlds, he found nothing but greed and death, blind as he was to the beauty of the worlds he found. Once again, Karn fell into depression and stagnated upon his plane. He was jarred from this malaise by the arrival of Karona upon Argentum, and he introduced himself as Lord Macht. After Karona was defeated, Karn took her and the Mirari to Argentum and turned the orb into the golem Memnarch, and left to wander the multiverse with Jeska. Unfortunately, the glistening oil in his Phyrexian powerstone caused him to leave traces of it on the planes he visited, including Argentum. When Memnarch came into contact with it, he decided to turn Argentum into Mirrodin, a metallic plane with its own ecosystem designed to transform Memnarch into a planeswalker.
Millennia later, Karn returned to Argentum, now turned to Mirrodin by an insane Memnarch. Much to his surprise, he found himself locked out of his own plane and barely able to pierce the veil Memnarch had unwittingly placed around it. With his abilities limited, he sent dreams to the nascent planeswalker Glissa Sunseeker. Eventually Memnarch fell and so did the veil he had made. Karn turned Memnarch back into the Mirari and left it in the care of Glissa, Slobad, and Geth.
 Time RiftsThree hundred years after the events of the Phyrexian Invasion, Karn returned to Dominaria at the request of Jhoira to aid her in sealing the time rifts tearing the multiverse apart. While attempting to close the rift over Tolaria, Karn traveled back in time to accomplish it during the Invasion itself when Barrin obliterated Tolaria, a corruption began to take hold of his mind. Sensing this, Karn proceeded to planeswalk throughout the Blind Eternities so he would not be followed across the multiverse - protecting any foolish enough to follow him from a monster of his own creation.
 Quest for Karn
After the events of Time Spiral, Karn retreated to Mirrodin's Core, being worshipped as the new Father of Machines.  When Phyrexia grew upon Mirrodin, Karn was trapped in his own mind, battling between himself and the role the Phyrexians were trying to force upon him.  Sheoldred told a Mirran spy to kill Karn so she can take his place, and pointed toward a citadel.
The dark oil leaked from his heart, changing Karn's silver body as he sat upon his throne. While the Phyrexian Praetors and their minions vied over him, each trying to use him to further their own causes, Karn had a moment of clarity. He sent out a mechanical guide to lead Venser and his party to the fully corrupted core of the plane once called Mirrodin. After many hardships they find the golem in bad shape in the center of the tainted world.
The Sylvok outcast Melira tells Venser and his party that the oil only turns a being into a full Phyrexian if the heart is fully corrupted. By the time Venser reached Karn in the core of Mirrodin it was already too late. Melira cleansed the golem's body of the Phyrexian taint but she couldn't cleanse the golem's heart. Knowing his own life would soon be forfeit due to his increasing affliction symptoms, Venser made the ultimate sacrifice. With his last remaining mana he gave his life and spark to Karn. Moments later Karn was released from the Phyrexian tyranny and mourned the loss of his friend briefly, but turned to battle the Phyrexians, stating 'he still has a lot of work ahead of him'. 
 In-game references
- Change of Heart
- Corrupted Conscience
- Distant Memories
- Energy Flux (Mercadian Masques)
- Imps' Taunt
- Karn's Touch
- Legacy Weapon (Tenth Edition)
- Pacifism (Tempest)
- Praetor's Counsel
- Sift (Stronghold)
- Stroke of Genius
- Torture Chamber
- Treasure Trove (Exodus)
Quoted or referred to:
- Agonizing Memories (Weatherlight)
- Argent Mutation
- Argentum Armor
- Beast of Burden
- Bottle Gnomes (Tempest)
- Fade Away
- Fit of Rage
- Flowstone Blade
- Power Matrix
- Scrivener (Exodus)
- Serrated Biskelion
- Steel Golem (Weatherlight)
- Stroke of Genius
- Tendrils of Despair
- Thran Golem (Urza's Destiny)
- Victual Sliver
- Wall of Tears
- Xanthic Statue
- Mark Rosewater. (December 03, 2007.) "Weather(light) Report", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Monty Ashley. (May 17, 2011.) "Shrines of Karn", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Doug Beyer. (April 25, 2011.) "The Golem's Legacy", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Monty Ashley. (April 25, 2011.) "Mirrodin Book Releases", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jenna Helland. (May 05, 2011.) "Dark Discoveries, Part 1", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jenna Helland. (May 12, 2011.) "Dark Discoveries, Part 2", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jenna Helland. (May 19, 2011.) "Dark Discoveries, Part 3", Daily MTG, magicthegathering.com, Wizards of the Coast.
|Crew: Gerrard Capashen • Sisay • Hanna • Tahngarth • Orim • Ertai • Karn • Mirri • Crovax • Rofellos • Starke • Squee • Multani|
|Other characters: Urza • Jhoira • Teferi • Selenia, Dark Angel • Volrath • Takara en-Dal • Cho-Manno • Serra • Rayne • Barrin • Gaea • Yawgmoth|
|Related pages: Dominaria • Bloodline Project • Rath • Stronghold • The Predator • Mercadia • Cho-Arrim • Serra's Realm • Phyrexian Invasion of Dominaria • Rathi Overlay • The Legacy|
|Weatherlight | Tempest block: Tempest • Stronghold • Exodus | Masques block: Mercadian Masques • Nemesis • Prophecy | Invasion block: Invasion • Planeshift • Apocalypse | Scourge|
|Rath Cycle: Rath and Storm | Masquerade Cycle: Mercadian Masques • Nemesis • Prophecy | Invasion Cycle: Invasion • Planeshift • Apocalypse | Onslaught Cycle: Scourge|