Swarm

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. While a single cloud of locusts might actually be hundreds of feet across, for game purposes a swarm is defined as a single creature with a space of 10 feet—gigantic hordes of bats or locusts 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 (for example, a bat swarm can squeeze through a space that a Tiny creature could squeeze through).

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 property 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

A whirring mass of quick, darting shadows sweeps closer. Hundreds of high-pitched squeaks fill the air.

A bat swarm is a mass of small, fierce carnivorous bats with a thirst for the blood of any creature unfortunate enough to cross their path.

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

A glistening, squirming mass of blue-black insects advances like a venomous army.

A centipede swarm is a crawling mass of voracious centipedes that can climb over obstacles to get at prey.

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

An angry buzz fills the air around a darting cloud of thousands of ruby-red insects.

Hellwasps are vicious, foul-tempered magical insects from the infernal planes. 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

A whirling, clacking cloud of voracious, grasshopperlike insects flutters closer, filling the air with a high-pitched buzz.

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

A squirming, squeaking horde of feral rats surges closer, teeth glistening in their slavering jaws.

A rat swarm is a mass of teeming, famished, disease-ridden rats. A swarm is composed of individuals very much like the rat described here, but in such great numbers, rats can become implacable hunters capable of killing a human with hundreds of bites.

A rat swarm sometimes can be found in the sewers and foundations of human cities.

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

A horrible, scuttling army of hand-sized spiders scrambles forward.

A spider swarm is a scuttling horde of venomous spiders.

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.