Swarm of Rats

Medium swarm of Tiny beasts, chaotic neutral

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Armor Class: 12

Hit Points: 36 (8d8)

Speed: 30 ft., climb 20 ft.

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STR	DEX	CON	INT	WIS	CHA
6 (−2)	14 (+2)	10 (+0)	2 (−4)	10 (+0)	4 (−3)

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Saving Throws: Dex +4

Skills: Stealth +6, Perception +2

Damage Resistances: Bludgeoning, Piercing, and Slashing from Nonmagical Attacks

Condition Immunities: Charmed, Frightened, Grappled, Paralyzed, Petrified, Prone, Restrained, Stunned

Senses: Darkvision 30 ft., Passive Perception 12

Languages: —

Challenge: 1 (200 XP)

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Traits

Swarm Form.
The Swarm of Rats can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny rat. The swarm cannot regain hit points or gain temporary hit points.

Keen Smell.
The swarm has advantage on Wisdom (Perception) checks that rely on smell.

Swarm Resilience.
When the swarm is reduced to half its hit points or fewer, it has disadvantage on attack rolls and ability checks until healed above half its hit points.

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Actions

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

Infectious Frenzy (Recharge 5–6).
The swarm erupts in a frenzy of biting and scratching. Each creature in the swarm’s space must succeed on a DC 12 Constitution saving throw or be poisoned for 1 minute. A poisoned creature can repeat the saving throw at the end of each of its turns, ending the effect on a success.

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Tactics

• The Swarm of Rats seeks to engulf foes in tight spaces such as tunnels, sewers, or ruined buildings, making escape difficult.
• It uses its Infectious Frenzy to weaken tougher foes early in combat.
• Prefers to remain out of reach of melee fighters, slipping through cracks and holes to bypass frontline defenders.
• If heavily damaged, it retreats to regroup or hides in shadows until it can attack again.

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Environment:

Urban sewers, ruins, caves, dark alleys.

Swarm of Rats

This churning mass of filthy, squealing rodents surges forward in a wave of fur and teeth. Individually small and weak, together they move with unsettling coordination, gnawing and clawing at anything in their path. The swarm pours through cracks and shadows, overwhelming creatures with sheer numbers and spreading disease as they bite.

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Rat Swarm
Tiny animal (Swarm)
Hit Dice	4d8 (13 hp)
Initiative	+2
Speed	15 ft. (3 squares), Climb 15 ft.
Armor Class	14 (+2 size, +2 Dexterity), touch 14, flat-footed 12
Base Attack/Grapple	+3/-
Attack	Swarm (1d6 plus disease)
Full Attack	Swarm (1d6 plus disease)
Space/Reach	10 ft./0 ft.
Special Attacks	Disease, distraction
Special Qualities	Half damage from slashing and piercing, Low-Light Vision, Scent, swarm traits
Saves	Fort +4, Ref +6, Will +2
Abilities	Strength 2, Dexterity 15, Constitution 10, Intelligence 2, Wisdom 12, Charisma 2
Skills	Balance +10, Climb +10, Hide +14, Listen +6, Spot +7, Swim +10
Feats	Alertness, Weapon Finesse
Environment	Any
Organization	Solitary, pack (2-4 swarms), or infestation (7-12 swarms)
Challenge Rating	2
Treasure	None
Alignment	Always neutral
Advancement	None
Level Adjustment	–

Combat

A rat swarm seeks to surround and attack any warm-blooded prey it encounters. A swarm deals 1d6 points of damage to any creature whose space it occupies at the end of its move.

Disease (Ex): Filth fever-swarm attack, Fortitude DC 12, incubation period 1d3 days, damage 1d3 Dexterity and 1d3 Constitution. The save DC is Constitution-based.

Distraction (Ex): Any living creature that begins its turn with a swarm in its square must succeed on a DC 12 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.

Skills: A rat swarm has a +4 racial bonus on Hide and Move Silently checks, and a +8 racial bonus on Balance, Climb, and Swim checks. A rat swarm can always choose to take 10 on all Climb checks, even if rushed or threatened. A rat swarm uses its Dexterity modifier instead of its Strength modifier for Climb and Swim checks. A rat swarm has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight

Swarm of Rats

CR 1
XP 400
Neutral Tiny animal (swarm)

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Init +2; Senses darkvision 60 ft., low-light vision, scent; Perception +5

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DEFENSE

• AC 14, touch 14, flat-footed 12 (+2 Dex, +2 size)
• hp 16 (3d8+3)
• Fort +4, Ref +5, Will +1
• Defensive Abilities swarm traits
• Immune weapon damage

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OFFENSE

• Speed 20 ft., climb 20 ft.
• Melee swarm (1d6 plus disease)
• Space 10 ft.; Reach 0 ft.
• Special Attacks distraction (DC 12), disease

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STATISTICS

• Str 2, Dex 15, Con 12, Int —, Wis 12, Cha 2
• Base Atk +2; CMB —; CMD —
• Skills Climb +10, Perception +5, Stealth +14
• Racial Modifiers +4 Perception, +8 Stealth
• SQ swarm traits

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ECOLOGY

• Environment any urban, underground, or ruins
• Organization solitary, pack (2–4 swarms), infestation (5–12 swarms)
• Treasure none

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SPECIAL ABILITIES

Disease (Ex)
Filth Fever—injury; Fort DC 12; onset 1d3 days; frequency 1/day; effect 1d3 Dex and 1d3 Con damage; cure 2 consecutive saves. The save DC is Constitution-based and includes a +2 racial bonus.

Distraction (Ex)
Any living creature that begins its turn in the swarm’s space must succeed on a DC 12 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.

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TACTICS

Before Combat
A swarm of rats hides in refuse, sewers, or shadows, using its high Stealth to ambush prey.

During Combat
The Swarm of Rats attempts to engulf and overwhelm the nearest living creature, targeting lightly armored foes and spellcasters. It uses its Distraction ability to disrupt enemy actions.

Morale
If reduced to half hit points, the Swarm of Rats retreats through cracks or tunnels. If cornered, it fights to the death.

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DESCRIPTION

A swarm of rats is a writhing tide of fur and teeth, driven by hunger and instinct. Though each rat is individually harmless, together they form a dangerous, nearly unstoppable mass capable of stripping flesh from bone. These swarms thrive in filth and decay, commonly found in cities, dungeons, and plague-ridden ruins.

Swarm infestations often herald deeper corruption—necromantic influence, foul cult activity, or the early signs of plague. In some dark places, these creatures are revered by vermin cultists or used as weapons by pestilence-worshiping druids and necromancers.