SRD:Imp

=IMP=

In its natural form, an imp stands almost 2 feet tall and weighs about 8 pounds.

Combat
Imps are craven, but not so timid as to pass up an opportunity for a surprise attack using their invisibility and alternate form ability. In its natural form, an imp attacks with the wicked stinger on its tail. It quickly flies out of reach if a foe manages to strike back effectively.

An imp’s natural weapons, as well as any weapons it wields, are treated as evil-aligned and lawful-aligned for the purpose of overcoming damage reduction.

Poison (Ex): Injury, Fortitude DC 13, initial damage 1d4 Dex, secondary damage 2d4 Dex. The save DC is Constitution-based and includes a +2 racial bonus.

Spell-Like Abilities: At will—detect good, detect magic, invisibility (self only); 1/day—suggestion (DC 15). Caster level 6th. The save DC is Charisma-based.

Once per week an imp can use commune to ask six questions. The ability otherwise works as the spell (caster level 12th).

Alternate Form (Su): An imp can assume other forms at will as a standard action. This ability functions as a polymorph spell cast on itself (caster level 12th), except that an imp does not regain hit points for changing form, and an individual imp can assume only one or two forms no larger than Medium. Common forms include monstrous spider, raven, rat, and boar. An imp can assume another form at will as a standard action. Each imp can assume one or two forms from the following list: Small or Medium monstrous spider, raven, rat, and boar.

See Wikipedia Entry: Imp