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Grimmlet Swarm

Large · Monstrosity · CR 14 · Unaligned

Source. Tome of Beasts 2

15 (natural armor)

152 (16d10+64)

Ability Scores

Core attributes and their modifiers.

STR

DEX

CON

INT

-4

WIS

CHA

Overview

Category Monsters

Size Large

Type Monstrosity

Alignment Unaligned

XP 11500

Initiative Bonus +1

Movement

Fly 30 ft (9.1 m)

Hover Yes

Senses

Blindsight 120 ft (36.6 m)

Passive Perception 10

Languages

understands Void Speech but can't speak

Resistances & Immunities

Damage Immunities

psychic

Damage Resistances

bludgeoning, piercing, slashing

Condition Immunities

blinded, charmed, deafened, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained, stunned

Traits

Enervating Maelstrom

When the grimmlet swarm dies, it explodes in a plume of ennui. Each creature within 20 feet of the grimmlet swarm must make a DC 17 Dexterity saving throw. On a failure, a creature takes 21 (6d6) psychic damage and suffers one level of exhaustion. On a success, a creature takes half the damage and doesn’t suffer exhaustion. Grimmlets damaged by this trait don’t Reproduce.

Innate Spellcasting (Psionics)

The grimmlet swarm’s innate spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). It can innately cast the following spells, requiring no components:
At will: maddening whispers, crushing curse, minor illusion
3/day each: hypnotic pattern, void strike, major image
1/day each: hallucinatory terrain

Maze of Edges

A creature that attempts to move out of or through the grimmlet swarm must succeed on a DC 15 Dexterity saving throw or take 9 (2d8) slashing damage.

Reproduce

When a grimmlet swarm takes damage from a spell and isn’t reduced to 0 hp, a number of new grimmlets equal to the spell’s level appear in unoccupied spaces within 10 feet of the grimmlet swarm. If the spell is a cantrip, only one grimmlet is created. New grimmlets aren’t subsumed into the swarm. Sixteen or more new grimmlets within 30 feet of each other can use their reactions to come together and form a new grimmlet swarm in a space within 5 feet of one grimmlet.

Swarm

The grimmlet swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny grimmlet. The swarm can’t regain hp or gain temporary hp.

Actions

Crystal Edges

+8 to hit. Hit: 4d8 psychic damage.

Melee Weapon Attack: +8 to hit, reach 0 ft., one creature in the swarm's space. Hit: 18 (4d8) slashing damage, or 9 (2d8) slashing damage if the swarm has half of its hp or fewer. The target must make a DC 17 Intelligence saving throw, taking 21 (6d6) psychic damage on a failed save, or half as much damage on a successful one.

Multiattack

The grimmlet swarm makes two attacks with its crystal edges.

About Grimmlet Swarm

Grimmlet Swarm is a large monstrosity with a Challenge Rating of 14. It has a unaligned alignment.

In combat, this creature maintains an Armor Class of 15 and possesses 152 hit points (derived from 16d10+64).

Grimmlet Swarm has communication capabilities including understands Void Speech but can't speak. This allows it to interact verbally with various creatures and characters.

GM Tips: Using Grimmlet Swarm

1 tips available

When using Grimmlet 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.

Player Guide: Facing Grimmlet Swarm

1 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.

Encounter Building Calculator

Standard Party Encounter (4-5 characters):

This creature is a medium encounter for a party of 4 characters of level 14.

Solo Encounter:

A single character of level 18 (up to level 20) can face this creature in a medium to hard encounter.

Experience Point Thresholds:

Medium: 21,000 XP
Hard: 31,500 XP
Deadly: 42,000 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 Grimmlet Swarm?: Grimmlet Swarm has a Challenge Rating of 14, making it appropriate for parties of level 14.0.
What type of creature is Grimmlet Swarm?: Grimmlet Swarm is a Large Monstrosity, which affects how certain spells and abilities interact with it.
What languages does Grimmlet Swarm speak?: Grimmlet Swarm can communicate in understands Void Speech but can't speak.