On Mirrodin, everything is made of metal—from forests to mountains to grass. Five suns cast their light on the plane, one for each color of mana.
Long ago, this metal plane was created by Karn, the silver golem built by the Planeswalker Urza. But something went wrong with Karn's creation. He unwittingly introduced a dark contagion: Phyrexian oil. Over the centuries, this oil has taken hold, infecting the land and breeding wave after wave of new horrors.
Even the Warden that Karn created to protect the plane grew unstable, gaining sentience and calling himself Memnarch. Over time, Memnarch grew paranoid and angry, feeling abandoned by his creator. As Memnarch's madness grew, so did his power. He kidnapped countless beings from other planes before he was finally defeated by the elf Glissa Sunseeker.
But all is still not well on Mirrodin. The first generations of Mirrans have vanished, returned to the planes from which they were taken. Meanwhile, the Phyrexian contagion continues to do its work. New Phyrexian horrors continue to emerge from Mirrodin's core, killing all Mirrans in their path and even counting the Mirran dead among their Phyrexian ranks.
But the Phyrexia factions are not unified in purpose. Its red-aligned faction, led by Urabrask, turns a blind eye to the citizens of Mirrodin, allowing them safe harbor.
The rift of the various mana factions makes New Phyrexia both stronger and weaker than ever before—stronger because it's more varied and adaptable, but weaker because it lacks unity of purpose.
Will any Mirrans survive? What new horrors await this brutal world? Will the Phyrexian infection spread to planes beyond?