Rust MonsterMedium monstrosity
Iron Scent. The rust monster can pinpoint, by scent, the location of ferrous metal within 5 meters of it.
Rust Metal. Any nonmagical weapon made of metal that hits the rust monster corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed. Non magical ammunition made of metal that hits the rust monster is destroyed after dealing damage.
Bite. Melee Weapon Attack: +3 to hit, reach 1 m. Hit: 5 (1d8 + 1) piercing damage.
Antennae. The rust monster corrodes a nonmagical ferrous metal object it can see within 1 meter of it. If the object isn’t being worn or carried, the touch destroys a 30-centimeter cube of it. If the object is being worn or carried by a creature, the creature can make a Difficulty 11 Reflex saving throw to avoid the rust monster’s touch.
If the object touched is either metal armor or a metal shield being worn or carried, its takes a permanent and cumulative −1 penalty to the Defense it offers. Armor reduced to a Defense of 10 or a shield that drops to a +0 bonus is destroyed. If the object touched is a held metal weapon, it rusts as described in the Rust Metal trait.
No concoctions, maneuvers, or spells
All creatures in this system should have maneuvers or spells. You should add some maneuvers or spells to this creature. If you do so, please make a suggestion on github so I can finish adding maneuvers and spells to all creatures via https://github.com/mlenser/kryx-rpg-issues/issues/9.