Nerve Swimmers (CR 10)

Fine Aberration (Swarm)
Alignment: Usually lawful evil
Initiative: +5 (Dex); Senses: darkvision 60 ft.
Languages: telepathy 100 ft.

AC: 23 (+8 size, +5 Dex), touch 23, flat-footed 18
Hit Dice: 12d8+12 (66 hp)
Fort +5, Ref +9, Will +9
Speed: 20 ft., burrow 20 ft., climb 20 ft.
Space: 10 ft./0 ft.
Base Attack +9; Grapple -
Attack: Swarm
Full Attack: Swarm
Damage: Swarm 3d6 plus flesh burrow
Special Attacks/Actions: Distraction, domination, flesh burrow, nerve strike, wracking pain
Abilities: Str 1, Dex 21, Con 12, Int 12, Wis 13, Cha 14
Special Qualities: discern lies, hive mind, immune to weapon damage, swarm traits
Feats: Ability Focus (domination); Ability Focus (flesh burrow); Ability Focus (wracking pain); Negotiator; Persuasive
Skills: Bluff +,5, Climb +13, Diplomacy +19, Hide +21, Intimidate +17, and Sense Motive +15
Advancement: None
Climate/Terrain: Any land and underground
Organization: Solitary or inquisition (2-8 swarms)
Treasure/Possessions: None

Source: Dragon #337

Distraction (Ex): Any living creature that begins its turn with a swarm in its square must succeed on a DC 17 Fortitude save or be nauseated for i round. The save DC is Constitution-based.

Domination (Ex): Once per day, a nerve swimmer swarm that inhabits a host can force the host to obey its commands. The host must succeed on a DC 19 Fortitude save or be affected as if by a dominate monster spell (caster level 6th). This control lasts for only 6 minutes. The nerve swimmers control the victim's body directly instead of the mind; therefore this ability is not mind-affecting. The save DC is Constitution-based.

Flesh Burrow (Ex): Any living creature damaged by a nerve swimmer swarm must succeed on a DC 19 Fortitude save or the swarm burrows into its flesh. A swam that succeeds on this attack is considered to inhabit its host; it can use its domination, nerve strike, wracking pain, and discern lies abilities, but not its distraction or swarm attack. A swarm might leave its host as a free action, but it is difficult to remove a swarm. To remove a burrowing nerve swimmer swarm, a heal spell or greater restorative magic must be cast upon the host (requiring a DC 22 caster level check). The save DC is Constitution-based.

Nerve Strike (Ex): Five times per day, a nerve swimmer swarm that inhabits a host can stop the host from taking conscious action by absorbing its nerve impulses. The host must succeed on a DC 17 Fortitude save or be affected as if by a hold monster spell (caster level 6th). The nerve swimmers control the victim's body directly instead of the mind; therefore this ability is not mind-affecting. The victim can attempt a saving throw every round to shake off the effects of the nerve strike. The save DC is Constitution-based.

Wracking Pain (Ex): Three times per day, a nerve swimmer swarm that inhabits a host can cause its host to suffer wracking pain. The host must succeed on a DC 19 Fortitude save or take 2 points of Strength and Dexterity damage, and must succeed on another DC 19 Fortitude save or take 4 points of Constitution damage (half damage on a successful save). The save DCs are Constitution-based.

Discern Lies (Sp): Three times per day, as a free action, a nerve swimmer swarm that inhabits a host can use discern lies as the spell (caster level 12th; Will DC 18 negates) on the host. The save DC is Charisma-based.

Hive Mind (Ex): Any nerve swimmer swarm with at least 1 hit point per Hit Die (or 12 hit points for a standard nerve swimmer swarm) forms a hive mind and is treated as a single monster for the purposes of mind-affecting effects. When a nerve swimmer swarm is reduced below this hit point threshold, it cannot burrow into flesh or inhabit a host.

Telepathy (Su): A nerve swimmer swarm can communicate telepathically with any creature within 100 feet that has an Intelligence score. The creature can respond to the nerve swimmers if it wishes - no common language is needed.

Skills: Nerve swimmers make Intimidate checks as though they were Large creatures.

Nerve swimmers have a +8 racial bonus on Climb checks. A nerve swimmer swarm can always choose to take 10 on Climb checks, even if rushed or threatened. A nerve swimmer swarm uses its Dexterity modifier instead of its Strength modifier for Climb checks.

Like any swarm, a nerve swimmer 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 infest the bodies of its prey, using them as puppets or fonts of information for their own agendas or the plans of their masters.

Swarm Subtype

A swarm is a collection of Fine, Diminutive, or Tiny creatures that acts as a single creature. A swarm has the characteristics of its type, except as noted here. A swarm has a single pool of Hit Dice and hit points, a single initiative modifier, a single speed, and a single Armor Class. A swarm makes saving throws as a single creature.

A single swarm occupies a square (if it is made up of nonflying creatures) or a cube (of flying creatures) 10 feet on a side, but its reach is 0 feet, like its component creatures. In order to attack, it moves into an opponent's space, which provokes attacks of opportunity. It can occupy the same space as a creature of any size, since it crawls all over its prey. A swarm can move through squares occupied by enemies and vice versa without impediment, although the swarm provokes attacks of opportunity if it does so. A swarm can move through cracks or holes large enough for its component creatures.

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 swarm of 15,000 centipedes is ten centipede swarms, each swarm occupying a 10-foot square.) The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.

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 lower causes it 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 an opponent.

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 spells and abilities (charms, compulsions, phantasms, patterns, and morale effects) if the swarm has an Intelligence score and a hive mind. A swarm takes half again as much damage (+50%) from spells or effects that affect an area, such as splash weapons and many evocation spells.

Swarms made up of Diminutive or Fine creatures are susceptible to high winds such as that created by a gust of wind spell. For purposes of determining the effects of wind on a swarm, treat the swarm as a creature of the same size as its constituent creatures (see Winds, page 95 of the Dungeon Master's Guide). For example, a swarm of locusts (a swarm of Diminutive creatures) can be blown away by a severe wind. Wind effects deal 1d6 points of nonlethal damage to a swarm per spell level (or Hit Dice of the originating creature, in the case of effects such as an air elemental's whirlwind). A swarm rendered unconscious by means of nonlethal damage becomes disorganized and dispersed, and does not re-form until its hit points exceed its nonlethal damage.

Swarm Attack: Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover. A swarm's statistics block has "swarm" in the Attack and Full Attack entries, with no attack bonus given. The amount of damage a swarm deals is based on its Hit Dice, as shown below.

Swarm HDSwarm Base Damage
21 or more5d6

A swarm's attacks are nonmagical, unless the swarm's description states otherwise. Damage reduction sufficient to reduce a swarm attack's damage to 0, being incorporeal, and other special abilities usually give a creature immunity (or at least resistance) to damage from a swarm. Some swarms also have acid, poison, blood drain, or other special attacks in addition to normal damage.

Swarms do not threaten creatures in their square, and do not make attacks of opportunity with their swarm attack. However, they distract foes whose squares they occupy, as described below.

Distraction (Ex): Any living creature vulnerable to a swarms 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; the exact DC is given in a swarm's description) negates the effect. Spellcasting or concentrating on spells within the area of a swarm requires a Concentration check (DC 20 + spell level). Using skills that involve patience and concentration requires a DC 20 Concentration check.