Rust Monster
Monster Manual (2025) p. 263
- Size
- Medium
- Type
- monstrosity
- Alignment
- unaligned
- AC
- 14
- Initiative
- 1
- Hit Points
- 33 (6d8+6)
- Speed
- walk 40 ft.
- Senses
- darkvision 60 ft.
- Passive Perception
- 11
- Challenge
- 1/2
- Environment
- underdark
Traits
Proficiency Bonus
+2
Iron Scent
The rust monster can pinpoint the location of ferrous metal within 30 feet of itself.
Actions
Multiattack
The rust monster makes one Bite attack and uses Antennae twice.
Bite
Melee Attack Roll: +3, reach 5 ft. Hit: 5 (1d8 + 1) Piercing damage.
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.
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 of the object.
Reactions
Reflexive Antennae
Trigger: An attack roll hits the rust monster. Response: The rust monster uses Antennae.
Other data
description
Rust monsters roam the Underdark searching for ferrous metal. When they find this material—whether natural veins, subterranean structures, or creatures' equipment—these beetle-like scavengers rush to feed. Using their feathery antennae, rust monsters dissolve metals such as iron and steel into rusted scrap. They easily gnaw through this corroded metal using their mandibles. Rust monsters usually ignore creatures without metal equipment, but they defend themselves if attacked.