Iron Scent: The rust monster can pinpoint, by scent, the
Location of ferrous metal within 30 feet 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 5 ft., one target. Hit: 5 (1d8 + 1) piercing damage.
Antennae: The rust monster corrodes a nonmagical ferrous metal object it can see within 5 feet of it. If the object isn't being worn or carried, the touch destroys a 1-foot cube of it. If the object is being worn or carried by a creature, the creature can make a DC 11
Dexterity 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 AC it offers.
Armor reduced to an AC 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.