This article is part of a series for both the April 2020 RPG Blog Carnival and the 2020 Blogging A to Z Challenge.

Phyrexia is an artificial plane of mechanical and biomechanical «life», an ecosystem comprised of metal, death, and tissue: a hellish world with an accelerated evolution of artifact creatures. It is also known as the Machine Hell and the Nine Hells (its concept of being divided into nine circles seems based on Dante Alighieri’s depiction of Hell in the Divine Comedy).

Phyrexia was not so different from Mirrodin until Yawgmoth arrived thousands of years ago, brought there by the planeswalker Dyfed. Yawgmoth, with the remnants and descendants of the phthisis-inflicted Thran humans, whom he saved through the process he referred to as «phyresis» (essentially the replacement of weak mortality with artifice) and from which he named the plane, came here when they were forced out of the Thran Empire as traitors. The ensuing war destroyed the nation of the Thran.

Yawgmoth gave Phyrexian organisms a purpose: to thrive, to grow beyond the confines of Phyrexia and into the rest of the Multiverse. Over hundreds of years, Phyrexia evolved priests and acolytes who extolled and worshiped Yawgmoth, as well as demons and abominations of infinite variety to kill for him. Over time a vast social order emerged, a horrifying food chain with church-like rites and rituals. Phyrexian organisms were judged by their ability to survive their nightmarish world. Successful ones were “evolved” with an unspeakable mixture of necrotic tissue and greasy metal. Eventually, Phyrexia created great Spore Engines and Plague Dreadnoughts – unimaginably huge, quasi-living artifact machines designed for war, which they used to invade Dominaria.

But they were not successful. After its destruction at the hands of the Weatherlight crew using the Legacy Weapon, the original Phyrexia was destroyed. Nontheless, stirrings on the plane of Mirrodin have given rise to a recreation of Phyrexia. Karn, Mirrodin’s Creator, had accidentally left some of his own Phyrexian Oil contagion within the core, that has begun to spread, corrupting the creatures there and driving the plane to phyresis, giving rise to a New Phyrexia.

«From void evolved Phyrexia. Great Yawgmoth, Father of Machines, saw its perfection. Thus the Grand Evolution began.»

For your campaign

Phyrexia is not just a civilization of necrotech horrors—it’s also a way of thinking, a perspective on organic flesh and on what makes an organism the best it can be. Phyrexians absorb and transform their victims not just to rule the plane, but for a cause—because they see non-Phyrexians as partial, imperfect, and incompleat.

New disease: Phyresis

Phyresis, or progressive generation, is the transformation of a living thing into a Phyrexian creature. After the process, the creature is considered to be compleated. As a process, phyresis was developed by Yawgmoth, when he wanted to save the remnants and descendants of the phthisis-inflicted Thran.

Thesaurus note: the word «pyrexia» is a medical term for «fever», and «compleat» is an archaic English term meaning «having all necessary or desired elements or skills».

Phyresis is brought about by glistening oil and compleation is the state of Phyrexian maturity and perfection, entailing the total replacement of all organic parts of the body, until nothing but artifice remains. The being retains its memory and personality, but often the traumatically painful process affects the latter.

1. Exposure. Glistening oil is the agent for phyresis, but some phyrexian creatures are able to infect other creatures through their attacks. If found by itself and got in contact with it, the character must succeed on a Constitution saving throw with a DC 15. If gotten by an attack, the DC is set by the attacking creature but the saving throw must be made at the end of the encounter. If the target is exposed to the glistening oil more than once in a given encounter, the saving throw is made only once, but with disadvantage.
2. Infection. When the character is infected by phyresis, it is at stage 1. The saving throw is made at the end of a long rest with the same DC. If the saving throw succeeds by 5 or more, then the stage is reduced by one step. If it fails by 5 or more, it is augmented by one step. If the disease enters a new stage, the effects of the new stage are added to the effects of the previous one.
3. Progression. The disease attempts to progress at the end of each long rest. During this, another character can attempt to treat the disease with a Medicine check with the same DC. If successful, the saving throw is rolled with advantage. As a house rule, you may consider having the saving throw being made every 24 hours if the characters try forgoing long rests (with a minimum time of 12 hours between checks).
   • Stage 0: Phyresis is averted.
   • Stage 1: Phyresis starts. you get a level of exhaustion. Magical healing only cures half its value. Make a death saving throw.
   • Stage 2: You get two levels of exhaustion. Your Constitution score is reduced by 2 permanently. Make a death saving throw.
   • Stage 3: You get two levels of exhaustion. You are unconscious. Magical healing doesn’t affect you. Make a death saving throw.
   • Stage 4: As you get one last level of exhaustion, you avert death by compleation. You become a phyrexian creature.

Given that stages 1, 2 and 3 have the characters make death saving throws, it’s possible that a creature will die by not being capable of enduring the pain produced by phyresis.

I recently watched Picard on Amazon Prime and it made me remember all the similarities between Phyrexia and the Borg. As one of the most terrible evils in the Magic multiverse, I always wanted to scare players off with the idea of a disease that would turn them into the creatures they were supposed to destroy.