- "All things must wither and die. Let root rot and bower blight, to feed the pestilence of abandoned hope."
- — Aghalhor the Bringer of Poxes
The Plague Lord's most infamous accomplishment sets the benchmark for all his other creations. Despite millennia of effort, he has never bettered that disease which bears his name: Nurgle's Rot. It is the most contagious, most rapacious, and most heinous of all sicknesses, poxes, and fevers he has ever produced. This vile disease is not only the living manifestation of physical corruption but is also a spiritual plague as it slowly erodes a victim's soul.
This perfect illness does not kill its host quickly; rather, it slowly turns the victim into a bloated living corpse teeming with the stuff of nightmares. Their blood curdles in their veins, their eyes grow together into a single globulous orb, and a horn sprouts from their head.
The illness does not merely affect the body, however -- it painfully corrupts the diseased mortal's soul to the point where the victim has to either end their own life or fully embrace the ways of Grandfather Nurgle. Only when death finally claims the victim will they realise the true blessing that has been visited upon them, as their soul is reborn in Nurgle's Garden in the Realm of Chaos in the immortal shape of a new Plaguebearer.
The grandest and most infamous of Nurgle's contagions, Nurgle's Rot is known by many names and has appeared on countless worlds, leaving entire populations desolated by this terrible daemonic pathogen. Nurgle's devoted Chaos Sorcerers take on all manner of diseases, serving as host to the creations of the Lord of Plagues. From this seething mass of decay and entropy, these devotees of pestilence summon forth the psychic echo of this paragon of plagues, inflicting it upon those nearby.
The infectious gift of Nurgle is cast outward to embrace all who stray too near to the Sorcerer. This vile disease can also be passed on by a Plague Knife, a corroded iron blade coated with rust and pestilence, to better spread Father Nurgle's blessing across the galaxy. Only those pure in his sight such as his Plague Marines are granted such a weapon, and any lesser being suffering even the slightest wound is gifted with one of his innumerable creations such as Nurgle's Rot. Those devoted to Nurgle are unaffected by this power.
Symptoms vary so wildly that no Imperial medic, physician or even a Space Marine Apothecary can deduce a cure, but the disease incorporates all the worst elements of every plague that has ever afflicted the mortals of the galaxy, slowly rendering the sufferer into a bloated, rotting, living corpse before they succumb to an eventual, agonising demise. Worse, its effects do not stop with death, for the soul of a mortal who succumbs to the infection belongs to Nurgle, doomed to serve forever as a Plaguebearer daemon. The Imperial Inquisition has destroyed entire worlds in the flame of Exterminatus at a single instance of Nurgle's Rot; such is the terror it provokes.
Nurgleite tradition has it that, for each person who contracts Nurgle's Rot, a seed like a rotten boil sprouts from the boughs of the mouldering willow trees which grow in Nurgle's Garden within the Realm of Chaos in the Warp. As the disease takes hold of the sufferer, that seed is said to swell into a vile, bubonic fruit which feeds off the afflicted person's soul like a tick gorging itself on its host's blood. When the bloated victim expires in a mess of bloody phlegm, the final traces of his soul are sucked into the engorged fruit, and the ripe flesh bursts apart as a new Plaguebearer daemon of the Plague Lord slips, slides and slithers into existence.
The longer an infected soul resists Nurgle's Rot, the more likely it is that they will survive the disgusting changes wrought upon them, and the more powerful a Plaguebearer they will become once the transformation is complete. Such individuals are sometimes possessed of a sheepish embarrassment that it took them so long to appreciate the blessings of their new existence. To one who has truly converted to Nurgle's cause, life as a bandy-legged mound of putrescent, boil-covered flesh and disgusting bodily functions is seen as the most fulsome of blessings rather than a despicable curse that will never end.
- Black Crusade: Core Rulebook (RPG), pp. 82, 166-167, 212, 216, 301, 355-356
- Codex: Chaos Daemons (6th Edition), pg. 47
- Codex: Chaos Daemons (4th Edition), pp. 34, 38
- Codex Heretic Astartes - Chaos Space Marines (8th Edition), pg. 94
- Realm of Chaos: The Lost and the Damned (1st Edition), pp. 18, 24
- Warhammer Fantasy Roleplay: Liber Infectus (3rd Ediiton), pg. 10
- White Dwarf 274 (UK), "Index Malleus: Daemon of the Warp"
- Flight of the Eisenstein (Novel) by James Swallow