Mirari

The Mirari was an artifact of unspeakable power that appeared on Otaria roughly a century after the Phyrexian Invasion.

Description
The word “mirari” was an ancient word for a fantastic wish-granting artifact and the Mirari certainly matched that description, tapping into its wielder's desires and making them real. However, the Mirari also inevitably caused disaster to strike the bearer, usually leading to their death. Another effect it had was that it caused intense longing in those that saw it, causing many individuals to become obsessed with owning it. It initiated a devastating cycle of warfare and magical disasters across Otaria before it was retrieved by its creator, Karn, who had only intended for it to be a probe. He took it to his artificial plane, Argentum, where he used it as the core of the golem he created as the plane's guardian, Memnarch.

Discovery
The Mirari was found by Chainer in an old mansion, where it called to the young cabalist with promises of power. However, Chainer instead decided it was only fit for the Cabal's leader to own and so presented it as a gift to the First, who put it in the Cabal's coffers as a prize in the upcoming three-day tournament. It was there that Kamahl first saw the Mirari and became obsessed with it. However, it was instead claimed by Lieutenant Kirtar of the Order as a reward for his role in defending Cabal City from a dragon attack. Kirtar took the artifact with the intention of destroying it, but it soon corrupted him with promises of glory. Instead, he took it to the Order's citadel and used it to kill Pianna, the human leader of the Order on Otaria. However, Kirtar was unable to end his spell, which went on to devastate the citadel and kill the Lieutenant.

The Mirari itself was recovered by Laquatus's minion Turg. The merman had been pursuing the artifact ever since Kirtar had claimed it and seized his chance to get hold of it. However, Laquatus's plan was frustrated when Turg gave the Mirari to Captain Satas, who then took it to Emperor Aboshan. Laquatus raced to recover it, but found that it had been lost within the royal treasure vaults. In order to get his hands on it, Laquatus made a deal with the cabalists that had been brought in to index the vaults: he would let them keep whatever valuable artifacts they wanted in exchange for giving him the Mirari when they found it. However, the Mirari was found first by the emperor himself.

Aboshan had gone down to the vaults in search of a magic weapon that he could use to secure his empire. As he gazed into the orb, he saw visions of a world covered entirely by water. He poured mana into the Mirari to try to make the vision a reality, creating a massive wave that flooded the northern third of Otaria. However, once again the spell ran out of control, devastating the Imperial capital and killing Aboshan just as it had Kirtar. The Mirari again escaped unharmed and fell into the hands of Braids, one of the cabalists that had been working in the vault. Like Chainer, Braids proved resistant to the device's charms and so rather than use it herself, she took it back into the hands of the Patriarch.

Problems in Cabal City
After having seen the disasters that the Mirari had caused to the Order and the Mer Empire, the Patriarch decided to be cautious with the orb. He decided to give it back to Chainer as he had resisted it before in the mansion, which suggested that he might be able to control it again. Chainer successfully used it to heal Kamahl after he was wounded defending Cabal City and also used it to create Laquatus a new champion, Burke. However, the Mirari eventually poisoned Chainer's mind as well, as he used it to overthrow the Cabal Patriarch and exile him to Aphetto, seizing control of Cabal City for himself. In a battle with his friend, Kamahl, Chainer was also overloaded by the Mirari, causing hordes of dementia horrors to appear and run riot in the city. As with Kirtar and Aboshan, he was overwhelmed by his own spell and died.

Kamahl took the Mirari with the intention of preventing it from causing harm, but was unable to resist its lure. He attached it to the pommel of his sword and tried to use its power to unite the Pardic barbarians under his rule. He was opposed by his mentor, Balthor, and his sister, Jeska, and so, in a fit of rage, he used his Mirari-enhanced sword to mortally wound Jeska. This act left Jeska with a consuming wound that could not be treated, so in order to make amends, Kamahl travelled to Krosa to try to heal her and to get rid of the Mirari.

Krosa
While in Krosa, Kamahl was attacked by Laquatus, who remained fixated on the orb. The two fought, with Kamahl finishing the merman by driving the Mirari-sword through Laquatus and into the ground, where he left it in the hope that it would be safe. However, the Mirari now began pouring energy into Krosa, causing the creatures there to mutate into gigantic, crazed beasts and even causing the plant life to grow out of control. As time wore on, the wave of mutating energy began to spread across Otaria, turning the normal creatures of the continent into misshapen, exaggerated versions of themselves. Wizards began to liquefy, Goblins grew feral and hunched, Clerics emanated light, and Soldiers became huge, speechless battle-tanks. This, along with the re-emergence of Karona and the slivers of the Riptide Project, led to a great deal of damage being done across the continent.

That was until Kamahl decided Karona had to be dealt with. He journeyed back into the heart of Krosa and slew the overgrown reanimated corpse of Laquatus in order to reclaim his sword. Under the guidance of Balthor's ghost, Kamahl eventually managed to master the Mirari-sword's power and tried to use it to slay Karona. Although Kamahl himself was unsuccessful, Karona was ultimately betrayed by her own minions, Sash and Waistcoat, who drove the blade through her back, killing Karona and releasing Jeska, who then became a planeswalker. Afterwards, Karn appeared and revealed the Mirari's humble origins and took it back to Argentum in order to end its dark influence.

Memnarch
Karn reshaped the Mirari as a sentient being, Memnarch. He named Memnarch as the protector of Argentum, and set off with his new planeswalker apprentice, Jeska, to explore planes unknown. Memnarch gradually became more self-aware, and eventually renamed the plane Mirrodin, also populating the hollow world with species from other planes.

After Memnarch's defeat, Karn returned to his plane and melted down Memnarch to his core, revealing the Mirari underneath. It was then left in Mirrodin in the care of Glissa, Slobad and Geth.