A Rust-Host has the outline of a person, or of the ox or dog it once was, but the substance is spent. Skin has dried to old leather, brown and cracked and tight over bones as thin as dry sticks. The eyes are empty pits. Hair hangs in flakes, nails have gone, and whatever the host wore or carried has rusted, rotted, or frayed with it: a mail shirt hangs in red tatters, a belt buckle is a crust.

It moves slowly, with a creak at every joint like an old gate, and behind it runs a trail of fine reddish-brown dust. The sound of a group of them is a dry rasp, like leaves crushed underfoot. They smell of rust and old cellars, a dry, metallic smell that lingers in the throat.

They would live in a Rustfall, where the ground goes soft and crumbly and cannot bear weight, and the ruins of what stood there slump around them. They would wander out of it after strength, and because rust spores travel on them, a host passing through a town could leave hinges, ploughshares, and rafters spotted with decay that spread after it had gone.

A Rust-Host seeks whatever is still strong and grips it. It does not strike or bite; it takes hold, of a wrist, a beam, a blade, and holds on, and what it holds corrodes to dust. Some keep scraps of who they were: a host that was a smith may still go to a forge and lay its hand on the anvil, and one that was a mother may come home and hold her strong son by the arm.

They are slow and patient and do not tire, and they never seem to hurry, as if they know that everything they reach for will fail in the end anyway.

A Rust-Host’s grip carries the Great Decay. Steel turns brittle and rusts through under its fingers; wood rots; a living limb withers, the skin cracking and the bone thinning. Rust spores shed from its body settle on metal, wood, and skin and spread from each spot as it crumbles.

What holds against it is preservation. Oiled steel, waxed wood, and a sealed reliquary keep a pocket of permanence it cannot easily eat, and things mended and maintained faster than it corrodes outlast it.

When the members of a Cult of the Final Dust crumbled with what they worship, what was left of them would walk on as Rust-Hosts. Others would be made from the wasted of a Rustfall. A host keeps decaying all the while and at last falls into a heap of brown dust and a few sticks of bone; the dust is still full of spores and would have to be swept up and sealed in clay, never scattered.

A Rust-Host takes the work of generations in an afternoon. Its danger falls hardest on what a community is proudest of: the mill wheel, the bridge, the armoury, the young and the strong. Communities near a Rustfall would keep oil, wax, and pitch close and mend constantly, and might count mending as a duty owed to the whole village.

Many would take the hosts for the dead of a cursed mine or a lost army. Iron would not ward them off, since iron is what they eat first, but oiled iron does hold, and a smith who believed a well-made blade could never be rusted by one would lose the blade proving it.