Imp, Melancholic (CR 3)

Small Outsider (Evil and Extraplanar)
Alignment: Always neutral evil
Initiative: +2 (Dex); Senses: darkvision 60 ft., Listen +7, and Spot +7

AC: 16 (+1 size, +2 Dex, +3 natural), touch 13, flat-footed 14
Hit Dice: 3d8+3 (16 hp); DR: 5/magic
Fort +4, Ref +4, Will +4
Speed: 30 ft., fly 30 ft. (average)
Space: 5 ft./5 ft.
Base Attack +3; Grapple +3
Attack: Claw +6 melee
Full Attack: 2 claws +6 melee and sting +1 melee
Damage: Claw 1d3, sting 1d3 plus imbalance
Special Attacks/Actions: Contagion, imbalance, improved grab
Abilities: Str 10, Dex 15, Con 13, Int 10, Wis 12, Cha 15
Special Qualities: fast healing 2, immunity to disease and poison, resistance to acid 5
Feats: Dodge; Weapon Finesse
Skills: Bluff +8, Diplomacy +4, Disguise +2 (+4 acting), Escape Artist +8, Heal +7, Hide +12, Intimidate +7, Listen +7, Move Silently +7, Spot +7, and Use Rope +2 (+4 with bindings)
Advancement: 4-6 HD (Small); 7-9 HD (Medium)
Climate/Terrain: Any evil-aligned plane
Organization: Solitary, gang (2-4 imps of mixed type), mob (5-12 imps of mixed type)
Treasure/Possessions: Standard

Source: Dragon #338

Contagion (Sp): Blinding sickness or filth fever; initial Fortitude DC 15.

Imbalance (Melancholy) (Su): The affected creature is struck with deep depression and takes a -2 penalty on attack rolls, saving throws, ability checks, skill checks, and weapon damage rolls. The first time the affected character attacks or is attacked in a subsequent melee, he may make another Will save to overcome this effect until the end of the encounter (after which the penalties return).

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.