Fiendish Familiar (CR 1/8)

Diminutive Outsider (Evil, Extraplanar, and Symbiont)
Alignment: Always neutral evil
Initiative: -3 (Dex); Senses: darkvision 60 ft., Listen +5, and Spot +5
Languages: Telepathy to host


AC: 11 (+4 size, -3 Dex), touch 11, flat-footed 11
Hit Dice: 1/2d8 (2 hp)
Fort +2, Ref -1, Will +1
Speed: 0 ft.
Space: 1 ft./0 ft.
Base Attack +1; Grapple -16
Attack: -
Full Attack: -
Damage: -
Special Attacks/Actions: -
Abilities: Str 3, Dex 4, Con 11, Int 12, Wis 9, Cha 6 (Ego: 8)
Special Qualities: Arcane education, enhance spellcaster, outsider traits, symbiont traits
Feats: Alertness
Skills: Concentration +4, Knowledge (any three) +5, Listen +5, Search +5, Sense Motive +3, Spellcrafr +5, and Spot +5
Advancement: -
Climate/Terrain: Any land and underground (Lower Planes)
Organization: Solitary (symbiont)
Treasure: -

Source: Fiend Folio

Combat

Fiendish familiars do not engage in combat, nor do they specifically aid their hosts in combat - although the enhancements they offer to spellcasting hosts can be significant in such situations.

Arcane Education (Ex): When grafted to a wizard, a fiendish familiar can teach the character one new spell of each spell level the character can cast. Each time the character gains access to a new spell level, the familiar teaches the character one new spell in addition to the two spells the character automatically gains for advancing a level. When grafted to a sorcerer or bard, a fiendish familiar can serve as a source of spell knowledge as described in the DMG 3.5 page 198.

Enhance Spellcaster (Ex): When grafted onto the body of any spellcaster, a fiendish familiar increases the character's effective spellcasting-related ability score by 2 for purposes of determining bonus spells. If the character has more than one spellcasting class, each relevant ability score is improved in this way.

Outsider Traits: A fiendish symbiont has darkvision (60-foot range). It cannot be raised or resurrected (though a wish or miracle spell can restore life).

Telepathy (Su): A fiendish symbiont can communicate telepathically with its host creature, if the host has a language.

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.

If a symbiont is grafted onto a visible part of the host creature's body, opponents can attack the symbiont itself instead of its host creature. This works the same way as attacking an object: The symbiont gains the benefit of the host's Dexterity modifier to AC instead of its own, and gains any deflection bonus to AC the host has as well. Its own size modifier and natural armor bonus, if any, apply. Attacking a symbiont instead of its host provokes an attack of opportunity from the host.

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.

Evil Subtype

A subtype usually applied only to outsiders native to the evil-aligned Outer Planes. Evil outsiders are also called fiends. Most creatures that have this subtype also have evil 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 an evil alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the evil subtype overcomes damage reduction as if its natural weapons and any weapons it wields were evil-aligned (see Damage Reduction).

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.