This hulking insectile monster has four legs, a strange propeller-shaped protrusion at the end of its tail, and two long, feathery antennae.
Rust Lord CR 6
During Combat Rust lords charge headlong into combat at the first hint of metal or other living beasts. Mad with hunger, they focus first on consuming any large metal objects with their rust ability before moving on to the comparatively small amounts of metal in their enemies’ blood, but they aren’t opposed to using their bite and bloodrust abilities to incapacitate foes who look like they’re attempting to escape.
Morale A rust lord never surrenders, and fights to the death.
Str 27, Dex 17, Con 19, Int 2, Wis 13, Cha 8
Base Atk +7; CMB +16; CMD 29 (33 vs. trip)
Feats Great Fortitude, Lightning Reflexes, Multiattack, Skill Focus (Perception), Toughness
Skills Perception +12, Stealth +7
A rust lord that makes a successful touch attack with an antenna causes the target metal to corrode, falling to pieces and becoming useless immediately. The touch can destroy up to a 10-foot cube of metal instantly. Magic armor and weapons, and other magic items made of metal, must succeed on a DC 23 Reflex save or be dissolved. Against creatures made of metal, a rust monster’s antennae deal 6d6+10 points of damage. The save DC is Constitution-based and includes a +4 racial bonus. A metal weapon that deals damage to a rust lord corrodes immediately. Wooden, stone, and other nonmetallic weapons are unaffected.
A rust lord can sense the twisting magnetic fields around metal objects to such a fine degree that it can perfectly discern the location of any metal object or creature with metallic blood (such as most humanoids) as if it could see it clearly, out to a range of 100 feet. Stone, wood, invisibility, and magical barriers are incapable of blocking this sense, and only an object containing significantly more metal, placed between the rust lord and its target, provides concealment or total concealment for this sense. For example, a man hiding behind a suit of discarded full plate has concealment, and one hiding behind a wall of iron has total concealment, though the rust lord might still be able to see him with its darkvision.
A brush from a rust lord’s antennae against flesh or thin clothing instantly draws forth the iron and other metallic minerals inside a creature’s blood, tearing through the skin in a fine mist and causing 1d4 points of Constitution damage.
Environment any underground, desert or jungle
Treasure incidental (no metal treasure)
The most feared variant of rust monster known, by far, is the notorious beast called the rust lord. It is found primarily in areas where metal is scarce or has been depleted, such as the barren deserts or the deep jungle caves. These hulking monstrosities are so regularly starved for nutrients that they have evolved to prey specifically on other living creatures, consuming the iron in their blood and tracking them by the twisting wake of their magnetic fields.