Rust Monster
Medium monstrosity, unaligned
Armor Class 14 (natural armor)
Hit Points 33 (6d8 + 6)
Speed 40 ft., swim 20 ft., climb 20 ft.
str
13 (+1)
dex
12 (+1)
con
13 (+1)
int
2 (-4)
wis
13 (+1)
cha
6 (-2)
Senses darkvision 60 ft., passive Perception 11
Languages -
Challenge 1/2 (100 XP)
Iron Scent. The rust monster can pinpoint the location of ferrous metal within 30 feet of itself.
Actions
Antennae. The rust monster targets one nonmagical metal object—armor or a weapon—worn or carried by a creature within 5 feet of itself. Dexterity Saving Throw: DC 11, the creature with the object. Failure: The object takes a -1 penalty to the AC it offers (armor) or to its attack rolls (weapon). Armor is destroyed if the penalty reduces its AC to 10, and a weapon is destroyed if its penalty reaches -5. The penalty can be removed by casting the Mending spell on the armor or weapon.
Bite. Melee Attack Roll: +3, reach 5 ft. 5 (1d8 + 1) Piercing damage.
Destroy Metal. The rust monster touches a nonmagical metal object within 5 feet of itself that isn't being worn or carried. The touch destroys a 1-foot Cube [Area of Effect]|XPHB|Cube of the object.
Multiattack. The rust monster makes one Bite attack and uses Antennae twice.