Swarms
are dense masses of Fine, Diminutive, or Tiny creatures that
would not be particularly dangerous in small groups, but can
be terrible foes when gathered in sufficient numbers. For game
purposes a swarm is defined as a single creature with a space
of 10 feet—gigantic hordes are actually composed of dozens
of swarms in close proximity. A swarm has a single pool of Hit
Dice and hit points, a single initiative modifier, a single
speed, and a single Armor Class. It makes saving throws as a
single creature.
Many different creatures can mass as swarms; bat swarms, centipede
swarms, hellwasp swarms, locust swarms, rat swarms, and spider
swarms are described here. The swarm’s type varies with
the nature of the component creature (most are animals or vermin),
but all swarms have the swarm subtype.
A swarm of Tiny creatures consists of 300 nonflying creatures
or 1,000 flying creatures. A swarm of Diminutive creatures consists
of 1,500 nonflying creatures or 5,000 flying creatures. A swarm
of Fine creatures consists of 10,000 creatures, whether they
are flying or not. Swarms of nonflying creatures include many
more creatures than could normally fit in a 10-foot square based
on their normal space, because creatures in a swarm are packed
tightly together and generally crawl over each other and their
prey when moving or attacking. Larger swarms are represented
by multiples of single swarms. A large swarm is completely shapeable,
though it usually remains contiguous.
COMBAT
In order to attack, a single swarm moves into opponents’
spaces, which provokes an attack of opportunity. It can occupy
the same space as a creature of any size, since it crawls all
over its prey, but remains a creature with a 10-foot space.
Swarms never make attacks of opportunity, but they can provoke
attacks of opportunity.
Unlike other creatures with a 10-foot space, a swarm is shapeable.
It can occupy any four contiguous squares, and it can squeeze
through any space large enough to contain one of its component
creatures.
Vulnerabilities of Swarms
Swarms are extremely difficult to fight with physical attacks.
However, they have a few special vulnerabilities,
as follows:
A lit torch swung as an improvised weapon deals 1d3 points
of fire damage per hit.
A weapon with a special ability such as flaming or frost deals
its full energy damage with each hit, even if the weapon’s
normal damage can’t affect the swarm.
A lit lantern can be used as a thrown weapon, dealing 1d4 points
of fire damage to all creatures in squares adjacent to where
it breaks.
BAT SWARM
Diminutive Animal (Swarm)
Hit Dice: 3d8 (13 hp)
Initiative: +2
Speed: 5 ft. (1 square), fly 40 ft. (good)
Armor Class: 16 (+4 size, +2 Dex), touch 14, flat-footed 12
Base Attack/Grapple: +2/—
Attack: Swarm (1d6)
Full Attack: Swarm (1d6)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, wounding
Special Qualities: Blindsense 20 ft., half damage from slashing
and piercing, low-light vision, swarm traits
Saves: Fort +3, Ref +7, Will +3
Abilities: Str 3, Dex 15, Con 10, Int 2, Wis 14, Cha 4
Skills: Listen +11, Spot +11
Feats: Alertness, Lightning Reflexes
Environment: Temperate deserts
Organization: Solitary, flight (2–4 swarms), or colony
(11–20 swarms)
Challenge Rating: 2
Treasure: None
Alignment: Always neutral
Advancement: None
Level Adjustment: —
A bat swarm is nocturnal, and is never found aboveground in
daylight.
Combat: A bat swarm seeks to surround and
attack any warm-blooded prey it encounters. The swarm deals
1d6 points of damage to any creature whose space it occupies
at the end of its move.
Distraction (Ex): Any living creature that
begins its turn with a swarm in its space must succeed on a
DC 11 Fortitude save or be nauseated for 1 round. The save DC
is Constitution-based.
Wounding (Ex): Any living creature damaged
by a bat swarm continues to bleed, losing 1 hit point per round
thereafter. Multiple wounds do not result in cumulative bleeding
loss. The bleeding can be stopped by a DC 10 Heal check or the
application of a cure spell or some other healing magic.
Blindsense (Ex): A bat swarm notices and locates
creatures within 20 feet. Opponents still have total concealment
against the bat swarm (but swarm attacks ignore concealment).
Skills: A bat swarm has a +4 racial bonus on Listen and Spot
checks. These bonuses are lost if its blindsense is negated.
CENTIPEDE SWARM
Diminutive Vermin (Swarm)
Hit Dice: 9d8–9 (31 hp)
Initiative: +4
Speed: 20 ft. (4 squares), climb 20 ft.
Armor Class: 18 (+4 size, +4 Dex), touch 18, flat-footed 14
Base Attack/Grapple: +6/—
Attack: Swarm (2d6 plus poison)
Full Attack: Swarm (2d6 plus poison)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, poison
Special Qualities: Darkvision 60 ft., immune to weapon damage,
swarm traits, tremorsense 30 ft., vermin traits
Saves: Fort +5, Ref +7, Will +3
Abilities: Str 1, Dex 19, Con 8, Int —, Wis 10, Cha 2
Skills: Climb +12, Spot +4
Feats: Weapon FinesseB
Environment: Underground
Organization: Solitary, tangle (2–4 swarms), or colony
(7–12 swarms)
Challenge Rating: 4
Treasure: None
Alignment: Always neutral
Advancement: None
Level Adjustment: —
Combat: A centipede swarm seeks to surround
and attack any living prey it encounters. A swarm deals 2d6
points of damage to any creature whose space it occupies at
the end of its move.
Distraction (Ex): Any living creature that
begins its turn with a centipede swarm in its space must succeed
on a DC 13 Fortitude save or be nauseated for 1 round. The save
DC is Constitution-based.
Poison (Ex): Injury, Fortitude DC 13, initial
and secondary damage 1d4 Dex. The save DC is Constitution-based.
Skills: A centipede swarm has a +4 racial bonus
on Spot checks and a +8 racial bonus on Climb checks, and uses
its Dexterity modifier instead of its Strength modifier for
Climb checks. A centipede swarm has a +8 racial bonus on Climb
checks and can always choose to take 10 on a Climb check, even
if rushed or threatened.
HELLWASP SWARM
Diminutive Magical Beast (Extraplanar, Evil, Swarm)
Hit Dice: 12d10+27 (93 hp)
Initiative: +10
Speed: 5 ft. (1 square), fly 40 ft.
Armor Class: 20 (+4 size, +6 Dex), touch 20, flat-footed 14
Base Attack/Grapple: +12/—
Attack: Swarm (3d6 plus poison)
Full Attack: Swarm (3d6 plus poison)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, inhabit, poison
Special Qualities: Damage reduction 10/magic, darkvision 60
ft., hive mind, immune to weapon damage, resistance to fire
10, low-light vision, swarm traits
Saves: Fort +10, Ref +14, Will +7
Abilities: Str 1, Dex 22, Con 14, Int 6, Wis 13, Cha 9
Skills: Hide +19, Listen +10, Spot +10
Feats: Ability Focus (poison), Alertness, Improved Initiative,
Iron Will, Toughness
Environment: A evil-aligned plane
Organization: Solitary, fright (2–4 swarms), or terror
(5–8 swarms)
Challenge Rating: 8
Treasure: None
Alignment: Always lawful evil
Advancement: None
Level Adjustment: —
A single hellwasp resembles a thumb-sized normal wasp, except
its carapace is gleaming black with ruby-red stripes, and its
compound eyes are an iridescent green. In swarms, hellwasps
form a collective hive mind intelligence with infernal cunning
and bloodlust.
Combat : Like any swarm, a hellwasp swarm
seeks to surround and attack any living prey it encounters.
A swarm deals 3d6 points of damage to any creature whose space
it occupies at the end of its move. The swarm can take over
the bodies of its prey and infest both the living and the dead,
using them as horrible living (or unliving) puppets to accomplish
acts of wickedness that a swarm of insects could never attempt.
A hellwasp swarm’s attack is treated as an evil-aligned
weapon and a magic weapon for the purpose of overcoming damage
reduction.
Distraction (Ex): Any living creature that
begins its turn with a hellwasp swarm in its space must succeed
on a DC 18 Fortitude save or be nauseated for 1 round. The save
DC is Constitution-based.
Inhabit (Ex): A hellwasp swarm can enter the
body of a helpless or dead creature by crawling into its mouth
and other orifices. Inhabiting requires 1 minute, and the victim
must be Small, Medium, or Large (although four swarms working
together can inhabit a Huge creature). The swarm can abandon
the body at any time, although doing this takes 1 full round.
Any attack against the host deals half damage to the hellwasp
swarm as well, although the swarm’s resistances and immunities
may negate some or all of this damage.
If a hellwasp swarm inhabits a dead body, it can restore animation
to the creature and control its movements, effectively transforming
it into a zombie of the appropriate size for as long as the
swarm remains inside. If a hellwasp swarm inhabits a living
victim, it can neutralize the effects of its own poison and
control the victim’s movement and actions as if using
dominate monster on the victim. The hellwasps quickly consume
a living victim, dealing 2d4 points of Constitution damage per
hour they inhabit a body. A body reduced to Constitution 0 is
dead.
A hellwasp-inhabited creature is relatively easy to spot, since
its skin crawls with the forms of insects inside. The swarm
is intelligent enough to attempt to hide beneath loose clothing
or a large cloak to keep its presence from being detected. The
swarm can attempt a Disguise check to conceal its inhabitation
of a host, with a –4 penalty if currently inhabiting a
Small host.
A remove disease or heal spell cast on an inhabited victim
forces the hellwasp swarm to abandon its host.
Poison (Ex): Injury, Fortitude DC 18, initial
and secondary damage 1d6 Dex. The save DC is Constitution-based.
Hive Mind (Ex): Any hellwasp swarm with at
least 1 hit point per Hit Die (or 12 hit points, for a standard
hellwasp swarm) forms a hive mind, giving it an Intelligence
of 6. When a hellwasp swarm is reduced below this hit point
threshold, it becomes mindless.
LOCUST SWARM
Diminutive Vermin (Swarm)
Hit Dice: 6d8–6 (21 hp)
Initiative: +4
Speed: 10 ft. (2 squares), fly 30 ft. (poor)
Armor Class: 18 (+4 size, +4 Dex), touch 18, flat-footed 14
Base Attack/Grapple: +4/—
Attack: Swarm (2d6)
Full Attack: Swarm (2d6)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction
Special Qualities: Darkvision 60 ft., immune to weapon damage,
swarm traits, vermin traits
Saves: Fort +4, Ref +6, Will +2
Abilities: Str 1, Dex 19, Con 8, Int —, Wis 10, Cha 2
Skills: Listen +4, Spot +4
Feats: —
Environment: Temperate plains
Organization: Solitary, cloud (2–7 swarms), or plague
(11–20 swarms)
Challenge Rating: 3
Treasure: None
Alignment: Always neutral
Advancement: None
Level Adjustment: —
A locust swarm is a cloud of thousands of winged vermin that
devours any organic material in its path.
Combat
A locust swarm surrounds and attacks any living prey it encounters.
A swarm deals 2d6 points of damage to any creature whose space
it occupies at the end of its move.
Distraction (Ex): Any living creature that
begins its turn with a locust swarm in its space must succeed
on a DC 12 Fortitude save or be nauseated for 1 round. The save
DC is Constitution-based.
Skills: A locust swarm has a +4 racial bonus
on Listen and Spot checks.
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 Dex), 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: Str 2, Dex 15, Con 10, Int 2, Wis 12, Cha 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 Dex
and 1d3 Con. 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 line.
SPIDER SWARM
Diminutive Vermin (Swarm)
Hit Dice: 2d8 (9 hp)
Initiative: +3
Speed: 20 ft. (4 squares), climb 20 ft.
Armor Class: 17 (+4 size, +3 Dex), touch 17, flat-footed 14
Base Attack/Grapple: +1/—
Attack: Swarm (1d6 plus poison)
Full Attack: Swarm (1d6 plus poison)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, poison
Special Qualities: Darkvision 60 ft., swarm traits, tremorsense
30 ft., vermin traits
Saves: Fort +3, Ref +3, Will +0
Abilities: Str 1, Dex 17, Con 10, Int —, Wis 10, Cha 2
Skills: Climb +11, Listen +4, Spot +4
Environment: Warm forests
Organization: Solitary, tangle (2–4 swarms), or colony
(7–12 swarms)
Challenge Rating: 1
Treasure: None
Alignment: Always neutral
Advancement: None
Level Adjustment: —
Combat
A spider swarm seeks to surround and attack any living prey
it encounters. A swarm deals 1d6 points of damage to any creature
whose space it occupies at the end of its move.
Distraction (Ex): Any living creature that
begins its turn with a spider swarm in its space must succeed
on a DC 11 Fortitude save or be nauseated for 1 round. The save
DC is Constitution-based.
Poison (Ex): Injury, Fortitude DC 11, initial
and secondary damage 1d3 Str. The save DC is Constitution-based.
Skills: A spider swarm has a +4 racial bonus
on Hide and Spot checks and a +8 racial bonus on Climb checks.
It uses its Dexterity modifier instead of its Strength modifier
for Climb checks. It can always choose to take 10 on a Climb
check, even if rushed or threatened.
