Nishruu (CR 6)

Large Outsider (Chaotic)
Alignment: Usually chaotic neutral
Initiative: +4; Senses: Listen +16 and Spot +16
Languages: Nishruu only

AC: 9 (-1 size), touch 9, flat-footed 9
Hit Dice: 9d8+30 (70 hp); DR: 10/magic
Fort +9, Ref +6, Will +10
Speed: Fly 20 ft. (perfect)
Space: 10 ft./5 ft.
Base Attack +9; Grapple -
Attack: Swarm of bites
Full Attack: Swarm of bites
Damage: Bite 2d6
Special Attacks/Actions: Absorb magic, distraction, swarm of bites
Abilities: Str -, Dex 10, Con 16, Int 13, Wis 15, Cha 13
Special Qualities: Charge magic, gaseous form, immune to mind-affecting effects, resistance to cold 10, vulnerabilities
Feats: Alertness; Improved Initiative; Iron Will; Toughness
Skills: Concentration +15, Knowledge (arcana) +13, Knowledge (history) +13, Knowledge (the planes) +13, Listen +16, Move Silently +12, Search +13, Spellcraft +15, and Spot +16
Advancement: 10-15 HD (Large); 16-27 HD (Huge)
Climate/Terrain: Any land
Organization: Solitary
Treasure/Possessions: None

Source: Lost Empires of Faerûn

Absorb Magic (Su): Nishruus feed on magic. They absorb any magical energy that comes in contact with their bodies, including spells targeted on them, magic items they envelop, and even spellcasters engulfed within their misty forms. This unusual diet has the following effects.

Distraction (Ex): Any living creature vulnerable to a swarm attack that begins its turn with a nishruu in its square is nauseated for 1 round (DC 17 Fortitude save negates). The save DC is Constitution-based. Spellcasting or concentrating on spells while in contact with a nishruu requires a Concentration check (DC 20 + spell level). Likewise, using any skill that involves patience and concentration requires a DC 20 Concentration check.

Swarm of Bites (Ex): Like a swarm, a nishruu doesn't make standard melee attacks. Instead, it deals automatic damage to any creature whose space it occupies at the end of its move, with no attack roll needed. This attack is not subject to a miss chance for concealment or cover. A nishruu does not threaten creatures in its square, nor can it make attacks of opportunity with its swarm of bites attack. However, it distracts foes whose squares it occupies, as described above.

Gaseous Form (Ex): Since its body is composed of mist, a nishruu can pass through small holes or narrow openings. It also has damage reduction 10/magic and immunity to poison and is not subject to extra damage from critical hits. Though a nishruu is vulnerable to cold- and fire-based attacks, such effects cannot form inside its gaseous body.

Immune to Mental Influence (Ex): Nishruus are completely unaffected by mind-affecting effects (charms, compulsions, phantasms, and morale effects).

Vulnerability (Su): A rod of absorption or ring of spell turning brought into contact with a nishruu has a 5% chance of destroying it immediately. The creature is absorbed with no harm to the item, though its color changes to a dusky red. If the item does not absorb the nishruu, it is negated in the same manner as other magic items.

Salt is poisonous to a nishruu, and a handful of thrown salt deals 2d10 points of damage to the creature.

Charge Magic (Su): When a nishruu is slain, its body dissipates and drifts away. Any charged magic item in contact with it when it dies gains an 1d6 additional charges. The enhancement bonus of a magic weapon that strikes the killing blow against a nishruu increases by 1 for 1d6 days.

Chaotic Subtype

A subtype usually applied only to outsiders native to the chaotic-aligned Outer Planes. Most creatures that have this subtype also have chaotic alignments; however, if their alignments change they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has a chaotic alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the chaotic subtype overcomes damage reduction as if its natural weapons and any weapons it wields were chaotic-aligned (see Damage Reduction).