A Comprehensive Guide to the Swarm of Rats in D&D 5e

Introduction

The swarm of rats is one of many unique and unsettling creatures in Dungeons & Dragons (D&D), but few challenge adventurers in all kinds of terrifying ways. Imagine being in a dark, damp dungeon, where the air smells of rot, and the silence is only broken by claws’ faint, scratching sound.

Then, suddenly, the floor itself seems to move—hundreds of small, scurrying bodies pour from the shadows. A swarm of rats might not be the most fearsome enemy at first glance, but their numbers and relentless nature can quickly turn them into a significant threat.

In this guide, we’ll take a deep dive into the swarm of rats, exploring their stats, abilities, lore, and practical tips for both Dungeon Masters (DMs) and players.

Whether you’re a seasoned DM looking to challenge your players in new ways or a player preparing for the unexpected, this guide will help you understand how to use or defeat these vermin in your next D&D campaign.

What is a Swarm of Rats?

A swarm of rats is exactly what it sounds like a collective mass of these tiny, aggressive creatures. While a single rat might be more of a nuisance than a threat, they become dangerous when they gather in overwhelming numbers.

In Dungeons & Dragons 5th Edition (D&D 5e), a swarm of rats is typically depicted as a tightly packed group of rats that move and act as one entity.

The swarm is often described as a writhing mass of fur, sharp claws, and gleaming eyes, its members scurrying over each other in chaotic patterns. They’re small, but their sheer numbers make them a formidable challenge. Their compact nature allows them to invade the personal space of larger creatures, gnawing and clawing with unrelenting force.

Basic Stats

While each rat might be weak, together, they’re a more dangerous force. Here’s a breakdown of the swarm of rats’ basic stats in D&D 5e:

Armor Class (AC): 10
Hit Points (HP): 24 (7d8 minus 7)
Speed: 30 feet
Senses: Darkvision 30 feet, passive Perception 10

Though their Armor Class is low, their numbers allow them to absorb some damage before being completely wiped out. Their Darkvision helps them navigate in the kind of environments they most commonly inhabit—dark dungeons, sewers, and city alleys.

Unique Traits

The swarm of rats isn’t just a mass of tiny creatures. They have some unique traits that set them apart from singular enemies:

Swarm: The swarm trait allows them to occupy another creature’s space and move through tight openings that might block other enemies. They’re not concerned with fighting fairly; they’ll climb over you, under you, and through any gaps they can find.
Keen Smell: Rats have an acute sense of smell, giving them an advantage in tracking or locating creatures even when they can’t see them. This makes them difficult to hide from and excellent at detecting vulnerable prey.

These traits combine to create a surprisingly versatile enemy that can challenge players in unique ways, often catching them off guard.

Abilities and Actions

The swarm of rats isn’t just a passive nuisance. They have several notable abilities and actions that can turn a seemingly mundane encounter into a dangerous situation.

Keen Smell

The Keen Smell trait gives the swarm of rats an advantage on Wisdom (Perception) checks that rely on smell. This means they can easily detect invisible or hidden creatures if they’re within smelling range. While it might not seem particularly dangerous at first, this ability can ruin the plans of players who rely on stealth or magical concealment to avoid detection.

For DMs, this trait is perfect for keeping the tension high in a scenario where the party is trying to sneak through rat-infested areas. It makes it much harder for players to avoid combat entirely, forcing them to confront the threat head-on.

Swarm

The Swarm trait is the most defining characteristic of the swarm of rats. This ability allows them to occupy another creature’s space and share that space without suffering penalties. In combat, this means they can move into the same square as a player character, representing the rats crawling all over their target, biting and scratching as they go.

What makes this particularly dangerous is the fact that the swarm’s attacks are considered to be from all angles. It’s not just one rat attacking you; it’s a horde. This can create the feeling of being overwhelmed, especially when combined with the swarm’s numbers. The swarm also takes half damage from non-magical attacks, making it more durable than it first appears.

Bite Attack

Though small, the rats in the swarm can still deal damage through their Bite attack. The swarm makes one melee weapon attack with its collective gnashing teeth:

Bite: +2 to hit, reach 0 feet, one target in the swarm’s space. Hit 2d6 piercing damage (or half damage if the swarm has half of its hit points or fewer).

While this attack might not seem particularly deadly, the constant pressure of the swarm and the fact that it can move through player spaces means that it can deal damage consistently, especially to characters with lower AC.

Lore and Background

Origins

Rats have always been a part of human history, often symbolizing disease, decay, and survival. In the world of D&D, swarms of rats have a similar reputation. Their origins in D&D lore often tie them to areas of civilization where filth and corruption are rampant. They’re frequently found in sewers, abandoned buildings, and places where food is scarce, thriving in the underbelly of society.

While they might not be the result of a grand magical event or a curse, their presence is a sign that something is wrong in the world. DMs can use this symbolism in their campaigns to represent the degradation of a city or the lurking danger beneath a seemingly peaceful town.

Habitat

Swarms of rats are most commonly found in urban areas where food is plentiful, but living conditions are harsh. Think sewers, alleyways, old warehouses, and decrepit parts of cities. They thrive in environments where they can scavenge for food and build nests away from predators.

Outside of cities, swarms of rats can be found in swamps, forests, or dungeons, often in places where decay and rot are prominent. They feed on whatever they can find, including corpses, rotting food, and even larger creatures that have fallen prey to disease or starvation.

Behavior

Rats are highly adaptable and opportunistic creatures, and swarms of rats in D&D are no different. They move with a singular purpose—whether it’s to find food or defend their territory. In a swarm, they act like a hive mind, coordinating their attacks to bring down larger prey.

Their movement is fast and erratic, giving the impression that they are almost uncontrollable, though, in truth, they are directed by the swarm’s overall need for survival. This means they are often found in places where there’s a food source or something that attracts them, such as the lair of a necromancer or in the aftermath of a bloody battle.

Using Swarm of Rats in Your Campaign

Encounter Ideas

Swarms of rats can be more than just random nuisances in your campaign. Here are a few ideas for how to incorporate them in unique and exciting ways:

Urban Infestation: The party is hired by a city official to investigate a growing rat problem in the sewers. What seems like a simple task quickly spirals out of control as the rats reveal themselves to be part of a larger, more sinister plot.
Necromancer’s Ally: A necromancer uses swarms of rats as minions, controlling them through dark magic. These swarms act as the first line of defense for the villain’s lair, overwhelming the party before they can even reach the necromancer.
Swamp Encounter: The players must travel through a swamp known to be infested with swarms of rats. As they journey through the muck, they realize the rats aren’t just there for food—they’re protecting something or someone deeper within the swamp.

Tactics for DMs

When using swarms of rats in combat, focus on their numbers and mobility. Their ability to occupy the same space as player characters makes them perfect for surrounding the party and overwhelming them. Consider these tactics:

Use tight spaces: Swarms of rats are more effective in small, confined spaces where they can easily trap the players and make it difficult to escape or maneuver.
Wear down spellcasters: Since they take half damage from non-magical attacks, swarms of rats are particularly dangerous to martial characters, forcing spellcasters to use precious resources to deal with them.
Ambush tactics: Swarms of rats are excellent for surprise attacks. Have them emerge from the shadows, dropping from ceilings or pouring out from walls.

Player Strategies

Fighting swarms of rats requires different tactics than dealing with a single monster. Here are a few tips for players:

Area-of-effect spells: Spells like Burning Hands or Thunderwave 5e are highly effective against swarms because they target multiple creatures at once. Taking out a chunk of the swarm with one spell can turn the tide of battle.
Flight and mobility: If possible, characters with high mobility or flight can avoid the swarm’s reach entirely. Use the environment to your advantage by climbing or staying out of range.
Control the battlefield: Use spells like Entangle or Web to slow down the swarm’s movement, giving the party time to deal damage or retreat to a safer position.

Swarm of Rats Variants and Homebrew Ideas

Variants

Though the standard swarm of rats is a formidable opponent, there are ways to make them even more interesting by introducing variants:

Plague Rats: These rats carry a deadly disease that infects anyone they bite. Add a Constitution saving throw to avoid becoming diseased after being bitten.
Shadow Rats: These rats are infused with shadow magic, making them more elusive and dangerous. They can move through darkness without being seen and are immune to damage from non-magical light sources.

Homebrew Ideas

For DMs who want to get creative, here are a few homebrew ideas for making your swarm of rats encounters stand out:

Undead Swarm: Create a swarm of zombie rats that refuse to die, even when reduced to 0 HP. These rats can continue fighting as long as at least one member of the swarm is still standing.
Elemental Rats: Imagine a swarm of fire-infused rats that leave behind a trail of flames as they scurry across the battlefield. Or a swarm of water rats that can swim through rivers and flood the area when they attack.

Swarm of Rats in Popular Culture

Appearances

Swarms of rats are not unique to D&D; they have appeared in various forms of popular culture, especially in fantasy and horror genres. In the D&D multiverse, swarms of rats have appeared in official campaigns and novels, often as harbingers of a larger, more dangerous threat lurking in the shadows.

Influence

Rats, especially in large numbers, have been a staple of horror and dark fantasy for centuries. From movies like Willard to video games like Dishonored, the concept of being overwhelmed by rats taps into primal fears. This imagery influences how swarms of rats are portrayed in D&D, adding an extra layer of unease and fear to encounters with these creatures.

Conclusion

Swarms of rats may not have the raw power of a dragon or the mystical abilities of a lich, but their sheer numbers and persistence make them a dangerous opponent in any D&D 5e campaign.

Whether you’re a DM looking for a way to challenge your players or a player who wants to be prepared for the unexpected, understanding the swarm of rats is essential. They are versatile, terrifying, and can turn a simple dungeon crawl into a deadly encounter.

Have you ever faced a swarm of rats in your D&D campaigns? Share your experiences in the comments, or try incorporating one into your next game. And for those looking to learn more about other creatures or tactical tips, check out our related posts on dungeon design and encounter strategies!

FAQ

Are swarms of rats dangerous to high-level players?

While swarms of rats might not pose a direct threat to high-level players, their ability to wear down resources and use the environment to their advantage can make them a tricky foe, especially when combined with other enemies.

Can a swarm of rats be affected by mind control spells?

Yes, but the swarm functions as a single entity in combat so that mind control would target the entire swarm rather than individual rats.

What happens if a swarm of rats is reduced to 1 HP?

As a swarm, their effectiveness decreases when they have fewer hit points. With only 1 HP left, they can still bite but will deal half damage.

Are there other creatures that use swarm mechanics?

Yes, D&D 5e includes other swarm creatures, such as swarms of insects or bats, which follow similar mechanics to the swarm of rats.

Can players tame or control a swarm of rats?

It’s possible for players with certain abilities, such as Speak with Animals or Animal Handling, to influence or even tame a swarm of rats, though this would depend on the DM’s ruling and the situation in the campaign.