Mind Leech (CR 1/8)

Fine Aberration (Symbiont)
Alignment: Usually lawful evil
Initiative: -4 (Dex); Senses: darkvision 60 ft., Listen +6, and Spot +6
Languages: understands Undercommon, does not speak, telepathy


AC: 14 (+8 size, -4 Dex), touch 14, flat-footed 14
Hit Dice: 1d8 (4 hp)
Fort +0, Ref -4, Will +6
Speed: 1 ft.
Space: 1/2 ft./0 ft.
Base Attack +0; Grapple -21
Attack: Bite +3 melee
Full Attack: Bite +3 melee
Damage: Bite attach
Special Attacks/Actions: Attach, mind blast, psionics
Abilities: Str 1, Dex 3, Con 11, Int 16, Wis 14, Cha 16 (Ego: 16)
Special Qualities: symbiont traits
Feats: Alertness (B); Iron Will; Spell Penetration (applies to psionics) (B)
Skills: Concentration +4, Hide +12, Knowledge (any one) +7, Listen +6, Move Silently +4, Spellcraft +7, and Spot +6
Advancement: -
Climate/Terrain: Any underground
Organization: Solitary (symbiont)
Treasure: -

Source: Fiend Folio

Combat

A mind leech is almost totally helpless when not attached to a host. It hides in wet areas and attacks creatures that pass through its space, using surprise to avoid attacks of opportunity.

Attach (Ex): If a mind leech hits with its bite attack, it burrows into the target's flesh and makes its way to the brain stem. Since the bite deals no damage and the leech secretes an anesthetic, the host is often unaware it has been bitten until the mind leech has established itself at the seat of the host's central nervous system.

Mind Blast (Su): This attack is a 60-foot cone. Anyone caught in this cone must make a Will save (DC 17) or be stunned for 1d4 rounds. Each time the mind leech uses this ability, it deals 1 point of Intelligence damage to the host. A mind leech without a host cannot use this ability.

Psionics (Sp): At will - charm monster, detect thoughts, dominate person, and suggestion. These abilities are as the spells cast by a 10th-level sorcerer (save DC 13 + spell level). Each time the mind leech uses its charm monster or suggestion powers, it deals 1 point of Intelligence damage to the host. Using its dominate person ability deals 2 points of Intelligence damage. A mind leech without a host cannot use these abilities (though it can detect thoughts).

Telepathy (Su): A mind leech can communicate telepathically with its host, if its host has a language.

Skills: A mind leech has a +4 racial bonus on Move Silently checks.

Symbiont Traits: When joined with a host, a symbiont gains a number of benefits. It acts on its host's turn each round, regardless of its own initiative modifier. It is not flat-footed unless its host is, and it is aware of any danger its host is aware of.

A symbiont never takes damage from attacks directed at the host. Like a worn magic item, a symbiont is usually unaffected by spells that damage the host, but if the host rolls a 1 on its saving throw, the symbiont is one of the "items" that can be affected by the spell. A symbiont uses its host's base saving throw bonuses if they are better than its own.

Share Spells (Su): Any spell the host creature casts on itself automatically also affects the symbiont. Additionally, the host may cast a spell with a target of "Self" on the symbiont instead of on itself. Likewise, a symbiont can choose to have any spell or spell-like ability it uses on itself also affect the host creature, and may cast a spell with a target of "Self" on its host instead of on itself. The host and symbiont can share spells even if the spells normally do not affect creatures of the host or symbiont's type. Spells targeted on the host by another spellcaster do not affect the symbiont, and vice versa.