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Rust Monster

Medium · Monstrosity · CR 1/2 · Unaligned

Source. 5e 2014 Rules

14 (natural armor)

27 (5d8+5)

1/2

Ability Scores

Core attributes and their modifiers.

STR

DEX

CON

INT

-4

WIS

CHA

-2

Overview

Category Monsters

Size Medium

Type Monstrosity

Alignment Unaligned

XP 100

Initiative Bonus +1

Movement

Walk 40 ft (12.2 m)

Swim 20 ft (6.1 m)

Climb 20 ft (6.1 m)

Crawl 20 ft (6.1 m)

Senses

Darkvision 60 ft (18.3 m)

Passive Perception 11

Environments

Caves Underworld

Traits

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.

Actions

Antennae

Cost 1

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.

Bite

Cost 1

+3 to hit, reach 5 ft (1.5 m). Hit: 1d8 thunder damage.

Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 5 (1d8 + 1) piercing damage.

About Rust Monster

Rust Monster is a medium monstrosity with a Challenge Rating of 1/2. It has a unaligned alignment.

In combat, this creature maintains an Armor Class of 14 and possesses 27 hit points (derived from 5d8+5).

GM Tips: Using Rust Monster

2 tips available

When using Rust Monster in your D&D 5e campaign, consider these tactical approaches:

Minion Strategy: Use as scouts or minions for larger threats
Group Tactics: Group 3-4 together to pose a moderate threat

Player Guide: Facing Rust Monster

2 strategies available

When your party encounters this creature, keep these strategies in mind:

Easy Target: This creature is weak - focus on other threats
Group Threat: Multiple can be dangerous - use area attacks

Encounter Building Calculator

Standard Party Encounter (4-5 characters):

This creature is a medium encounter for a party of 4 characters of level 1.

Solo Encounter:

A single character of level 2 (up to level 20) can face this creature in a medium to hard encounter.

Experience Point Thresholds:

Medium: 75 XP
Hard: 112 XP
Deadly: 150 XP

Based on D&D 5e Dungeon Master's Guide encounter building guidelines. CR roughly equals party level for medium encounters.

Frequently Asked Questions

What is the challenge rating of Rust Monster?: Rust Monster has a Challenge Rating of 1/2, making it appropriate for parties of level 0.5.
What type of creature is Rust Monster?: Rust Monster is a Medium Monstrosity, which affects how certain spells and abilities interact with it.