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Swarm of Rats

Medium Swarm of Tiny Beasts · · CR 1/4

  • Swarm of Tiny Beasts
  • Medium
  • Tier 1

CR 1/4 medium swarm of tiny beasts, unaligned — that's Swarm of Rats. Native to swamp and urban. Sourced from Monster Manual (5e 2014) and Monster Manual (5.5e 2024).

Stat Block

Challenge Rating
1/4
Type
Swarm of Tiny Beasts
Size
Medium
Alignment
Speed
Habitats
Swamp, Urban
Sources
Monster Manual (5e 2014), Monster Manual (5.5e 2024)

Ecology

Rats follow humanoid civilization wherever it spreads, exploiting grain stores, refuse heaps, and sewage systems. A breeding pair produces dozens of offspring per year, and uncontrolled populations explode within weeks. Rat swarms form in plague conditions when food is abundant or when a single warren is disturbed. They carry diseases between hosts, making them ecological vectors as much as predators. Cats, weasels, and certain owls suppress populations, but rats persist anywhere humans live.

Behaviour

Rats are intelligent for their size, capable of solving puzzles and recognizing individual humans. A swarm acts on collective instinct, fleeing or attacking based on shared scent cues. They prefer dim, enclosed spaces and avoid direct daylight. Bold swarms enter homes through walls and floors, and they remember escape routes. Some city watches employ trained rat-catchers who command small swarms as living lockpicks for tight spaces.

Origin

Rats are the great commensal of mortal civilization, traveling on every cart and ship since the first cities rose. No origin myth claims them as divine; they are simply ubiquitous. Wererat scholars argue rats are the rightful inheritors of every fallen empire and that lycanthropy among humans merely formalizes a pre-existing alliance between species. Most cities reject this claim but quietly tolerate the wererat thieves' guilds nonetheless.

All Swarm of Tiny BeastssSwampUrban

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Frequently Asked Questions about Swarm of Rats

What is the challenge rating of Swarm of Rats?
On the bestiary CR scale, Swarm of Rats sits at 1/4. It works against low-level groups.
What type of creature is Swarm of Rats?
By creature type, Swarm of Rats is a swarm of tiny beasts, medium size.
Where does Swarm of Rats live?
Swarm of Rats is typically encountered in Swamp, Urban.
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Scannable QR code encoding the URL https://www.doungim.com/dnd/monsters/swarm-of-rats. Point a phone camera at this code to open the Swarm of Rats page on your mobile device — useful at the table when a DM's laptop or a printed sheet is showing the page.