Rusted Wyrm

Construct Victims of a Supernatural Curse

Habitat Coastal, Forest — Treasure Individual

The supernatural Rusting curse that pervades the Moonshae Isles manifests as a thin scrim of iron over a living creature's skin. This coarse iron rusts easily, turning the creature a sickly orange gray. Unchecked, this curse transforms the victim into a Rusted, an animated iron caricature of itself that sheds flakes of toxic rust.
As the Rusting curse hardens the skin, it also hollows out the mind. Rusted creatures despise unspoiled nature and are compelled to destroy it when they can.

Other Rusted. You can turn any Beast, Fey, Giant, Humanoid, or Monstrosity into a Rusted version of itself by doing the following: change the creature's type to Construct, and give it Immunity to Poison damage and the Exhaustion, Petrified, and Poisoned conditions.
A Rusted wyrm is a draconic colossus capable of phenomenal devastation. Although some Rusted wyrms evaporate rivers and destroy springs, others venture further underwater to wreck coral reefs and boil the sea.