Swarm, Viper (CR 3)

Medium Animal (Swarm-Diminutive)
Alignment: Always neutral
Initiative: +2 (Dex); Senses: low-light vision, scent, Listen +7, and Spot +7

AC: 16 (+2 Dex, +4 natural), touch 12, flat-footed 14
Hit Dice: 5d8+5 (27 hp)
Fort +5, Ref +6, Will +2
Speed: 15 ft., climb 15 ft.
Space: 5 ft./0 ft.
Base Attack +3; Grapple -
Attack: Swarm
Full Attack: Swarm
Damage: Swarm 1d6 plus poison
Special Attacks: Distraction (DC 13), poison
Abilities: Str 1, Dex 15, Con 12, Int 1, Wis 12, Cha 2
Special Qualities: Hive mind, swarm traits
Feats: -
Skills: Balance +10, Climb +12, Hide +8, Listen +7, and Spot +7
Climate/Terrain: Warm land and underground
Organization: Swarm

Source: Fiend Folio

A single snake no more than a foot long is rarely a threat to seasoned adventurers, no matter how virulent its venom.

More than a hundred such snakes writhing together in a single mass, however, is a waking nightmare.

The individual snakes that make up a viper swarm are 8 to 12 inches long, with black scales marked by red, orange, or yellow bands, lines, or arrowlike markings. As a swarm, they form a living carpet of wriggling snakes and crawl over one another and anything in their path, biting and injecting their deadly poison.


A single Diminutive viper's poison is painful but not deadly; several doses of it, however, can bring down an elephant. Viper swarms overwhelm their prey with poison, then feast on its still-warm flesh.

A viper swarm can be summoned using a summon nature's ally VI spell.

Poison (Ex): A viper swarm delivers its poison (Fort DC 13 negates) with each swarm attack. Initial and secondary damage are the same (1d4 Con).

Hive Mind (Ex): A viper swarm has a hive mind, making it susceptible to mind-affecting spells. For purposes of such spells, the swarm is a single creature of the animal type.

Scent (Ex): A viper swarm can detect approaching enemies, sniff out hidden foes, and track by sense of smell.

Skills: Viper swarms have a +4 racial bonus on Hide, Listen, and Spot checks, and a +8 racial bonus on Balance checks. They use their Dexterity modifier for Climb checks and have a +8 racial bonus on Climb checks and can always choose to take 10 on Climb checks, even if rushed or threatened.

Distraction (Ex): Any non-mindless creature vulnerable to a swarm's damage that begins its turn with a swarm in its square is nauseated for 1 round; a Fortitude save )DC 10 + 1/2 swarm's HD + swarm's Con modifier) negates the effect. Spellcasting or concentrating on spells within the area of a swarm requires a Concentration check (DC 20 + spell level). Using skills requiring patience and concentration requires a Concentration check )DC 20).

Swarm Traits: A swarm has no clear front or back and no discernible anatomy, so it is not subject to critical hits or flanking. A swarm made up of Tiny creatures takes half damage from slashing and piercing weapons. A swarm composed of Fine or Diminutive creatures is immune to all weapon damage.

Reducing a swarm to 0 hit points or fewer causes the swarm to break up, though damage taken until that point does not degrade its ability to attack or resist attack. Swarms are never staggered or reduced to a dying state by damage. Also, they cannot be tripped, grappled, or bull rushed, and they cannot grapple another.

A swarm is immune to any spell or effect that targets a specific number of creatures (including single-target spells such as disintegrate), with the exception of mind-affecting effects if the swarm has an Intelligence score and a hive mind. A swarm takes a -10 penalty on saving throws against spells or effects that affect an area, such as many evocation spells or grenadelike weapons. If the area attack does not allow a saving throw, a swarm takes double damage instead,

Swarms made up of Diminutive or Fine creatures are susceptible to high winds such as that created by a gust of wind spell. To determine the effect of wind on a swarm, treat the swarm as a creature of the same size as its constituent creatures. For example, a swarm of Abyss ants (Diminutive creatures) can be blown away by a severe wind. Wind effects deal 1d6 points of subdual damage to the swarm per spell level or Hit Die of the originating creature, in the case of effects such as an air elemental's whirlwind). A swarm that takes subdual damage sufficient to exceed its current hit points becomes disorganized and dispersed, and does not re-form until its current hit points exceed its subdual damage.