Locust Swarm, Bloodfiend (CR 8)

Medium Vermin (Extraplanar and Swarm-Fine)
Alignment: Always chaotic evil
Initiative: +4 (Dex); Senses: darkvision (60-foot range)


AC: 19 (+4 Dex, +5 natural), touch 14, flat-footed 15
Hit Dice: 14d8+28 (91 hp)
Fort +11, Ref +8, Will +5
Speed: 20 ft., fly 20 ft. (perfect)
Space: 10 ft./0 ft.
Base Attack +10; Grapple -
Attack: Swarm
Full Attack: Swarm
Damage: Swarm 3d6 plus energy drain
Special Attacks: Distraction (DC 19), energy drain
Abilities: Str 1, Dex 18, Con 14, Int -, Wis 13, Cha 11
Special Qualities: Reanimate, swarm traits, vermin traits
Feats: -
Skills: -
Advancement: -
Climate/Terrain: Any land and underground (Abyss)
Organization: Solitary or plague (10-40 swarms)
Treasure/Possessions: -

Source: Fiend Folio

Whereas the common locust poses a menace only to plants and crops, deadlier strains, influenced by magic or fiendish will, attempt to tear the flesh from any creature they encounter. These creatures, although too small individually to pose a threat to most creatures, can quickly engulf and devour unprepared victims.

Combat

Created to carry the horrors of the Abyss to other planes, bloodfiend locusts feast not only on the flesh of their victims, but on their very life force as well. As a swarm of bloodfiend locusts moves through a region, those who fall prey to the creatures rise again in twisted undead forms and are tainted not only by the forces of undeath, but also by the evil of the Abyss itself.

Energy Drain (Su): Living creatures hit by a bloodfiend locust swarm gain one negative level. If the negative level has not been removed (with a spell such as restoration) before one day has passed, the afflicted opponent must succeed on a Fortitude save (DC 19) to remove it.

Reanimate (Su): A humanoid or monstrous humanoid killed by the energy drain attack of a bloodfiend locust swarm rises 2d6 hours later as a fiendish vampire spawn.

Vermin Traits: A locust swarm is immune to all mind-affecting effects (charms, compulsions, phantasms, patterns, and morale effects). It also has darkvision (60-foot range).

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.