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Infernal Swarm

Huge · Fiend · CR 12 · Lawful Evil

Source. Tome of Beasts 2

16 (natural armor)

150 (20d12+20)

Ability Scores

Core attributes and their modifiers.

STR

DEX

CON

INT

-1

WIS

CHA

Overview

Category Monsters

Size Huge

Type Fiend

Alignment Lawful Evil

XP 8400

Initiative Bonus +3

Movement

Walk 25 ft (7.6 m)

Fly 40 ft (12.2 m)

Swim 12 ft (3.7 m)

Climb 12 ft (3.7 m)

Crawl 12 ft (3.7 m)

Hover Yes

Senses

Darkvision 120 ft (36.6 m)

Passive Perception 11

Languages

understands Infernal but can't speak, telepathy 60.0 ft (18.3 m).

Resistances & Immunities

Damage Immunities

fire, poison

Damage Resistances

bludgeoning, cold, piercing, psychic, slashing

Damage Vulnerabilities

thunder

Condition Immunities

charmed, frightened, paralyzed, petrified, poisoned, prone, restrained, stunned

Traits

Devil’s Sight

Magical darkness doesn’t impede the infernal swarm’s darkvision

Magic Resistance

The infernal swarm has advantage on saving throws against spells and other magical effects.

Shaped Swarm

As a bonus action, the swarm can shape itself into a Huge fiend or back into a shapeless mass. Its statistics are the same in each form, and it can’t regain hp or gain temporary hp. If a creature is more than 10 feet away from the infernal swarm, it must take an action to visually inspect the fiend form and succeed on a DC 25 Intelligence (Investigation) check to discern the Huge fiend is actually a swarm of Small insects. A creature within 10 feet of the swarm immediately discerns the truth.

While in fiend form, it can wield weapons and hold, grasp, push, pull, or interact with objects that might otherwise require a more humanoid form to accomplish. If the infernal swarm takes thunder damage while in its fiend form, it immediately changes to its shapeless form.

While in shapeless form, it can occupy another creature’s space and vice versa and can move through any opening large enough for a Small fiend, but it can’t grapple or be grappled.

Actions

Bites

+9 to hit. Hit: 8d6 piercing damage.

Melee Weapon Attack: +9 to hit, reach 0 ft., one target in the swarm's space. Hit: 28 (8d6) piercing damage, or 14 (4d6) piercing damage if the swarm has half its hp or fewer.

Multiattack

In fiend form, the infernal swarm makes three attacks: two with its scimitar and one with its slam, or three with its scimitar. In shapeless form, it makes three attacks with its bites.

Poisonous Barb

+8 to hit, range 30/120 ft (9.1/36.6 m). Hit: 2d6+3 poison damage.

Ranged Weapon Attack: +8 to hit, range 30/120 ft., one target. Hit: 10 (2d6 + 3) piercing damage, and the target must make a DC 17 Constitution saving throw, taking 18 (4d8) poison damage on a failed save, or half as much damage on a successful one.

Scimitar

+9 to hit, reach 10 ft (3 m). Hit: 3d6+4 slashing damage.

Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 14 (3d6 + 4) slashing damage.

Slam

+9 to hit, reach 10 ft (3 m). Hit: 4d6+4 piercing damage.

Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 18 (4d6 + 4) bludgeoning damage, and the target is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the infernal swarm can't slam another target. In addition, at the start of each of the target's turns, the target takes 14 (4d6) piercing damage.

About Infernal Swarm

Infernal Swarm is a huge fiend with a Challenge Rating of 12. It has a lawful evil alignment.

In combat, this creature maintains an Armor Class of 16 and possesses 150 hit points (derived from 20d12+20).

Infernal Swarm has communication capabilities including understands Infernal but can't speak, telepathy 60 ft.. This allows it to interact verbally with various creatures and characters.

GM Tips: Using Infernal Swarm

2 tips available

When using Infernal Swarm in your D&D 5e campaign, consider these tactical approaches:

Flight Control Strategy: Target flying creatures with spells like 'Hold Person', 'Web', or 'Grease' to ground them. Without flight restriction, they can escape melee range easily. Consider area denial spells below their flight altitude to force them into disadvantageous positions.
Telepathic Communication: This creature can communicate telepathically, making it excellent for coordination with allies. Silence spells won't stop its communication. Consider 'Mind Blank' or abilities that block telepathy.

Player Guide: Facing Infernal Swarm

2 strategies available

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

Counter Flight Advantage: This creature can fly! Use ranged attacks, reach weapons, or spells like 'Thunderwave' to push it away. Consider 'Gust of Wind' or 'Earthbind' to ground it. Melee characters need fly speed or flight magic to engage.
Telepathy Awareness: This creature communicates telepathically! It can coordinate with allies silently. Silence won't stop it. Use 'Mind Blank' or abilities that block telepathy. Be cautious of mental attacks.

Encounter Building Calculator

Standard Party Encounter (4-5 characters):

This creature is a medium encounter for a party of 4 characters of level 12.

Solo Encounter:

A single character of level 16 (up to level 20) can face this creature in a medium to hard encounter.

Experience Point Thresholds:

Medium: 15,600 XP
Hard: 23,400 XP
Deadly: 31,200 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 Infernal Swarm?: Infernal Swarm has a Challenge Rating of 12, making it appropriate for parties of level 12.0.
What type of creature is Infernal Swarm?: Infernal Swarm is a Huge Fiend, which affects how certain spells and abilities interact with it.
What languages does Infernal Swarm speak?: Infernal Swarm can communicate in understands Infernal but can't speak, telepathy 60 ft..