Rust Monster

Iron Scent. The rust monster can pinpoint, by scent, the location of ferrous metal within 30 feet of it.

Monstrosity Resilience. The rust monster is resistant to exhaustion and to the frightened condition.

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. Nonmagical ammunition made of metal that hits the rust monster is destroyed after dealing damage.

Spider Climb. The rust monster can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Bite. _Melee Weapon Attack:_ +3 to hit, reach 5 ft., one target. _Hit:_ 8 (2d6+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 DEX save to avoid the rust monster's touch.<br>If the object touched is either metal armor or a metal shield being worn or carried, it 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.

Iron Dash. The rust monster moves up to half its speed toward a source of ferrous metal it can sense.