The Great Unclean One is Nurgle's chosen champion, a mountain of decaying flesh that serves as both general and living plague-vault of its patron. These greater daemons are vast beyond reckoning, their swollen bodies ruptured and reformed a thousand times over, home to countless lesser creatures that swarm within their rotting bulk. Despite their revolting appearance, they radiate a horrible warmth and good humour, greeting foes as if welcoming them to a shared feast of corruption.
In battle, a Great Unclean One is nearly unkillable. Its enormous mass absorbs punishment that would obliterate lesser beings, and each wound simply spills forth more contagion. It wields diseased weapons and exhales clouds of pestilence, but its true power lies in its resilience and the strength it lends the daemons around it. As a commander it is patient and paternal, herding its shambling legions forward with fond encouragement. To slay one is a labour of grim persistence, and even in apparent death its corruption lingers, seeping into the land it defiled.