Malaugrym (CR 4)

Medium Outsider (Evil, extraplanar, and Shapechanger)
Alignment: Always chaotic evil
Initiative: +2 (Dex); Senses: darkvision 60 ft., Listen +9, and Spot +9
Languages: Common, Malaugrym

AC: 17 (+2 Dex, +5 natural), touch 12, flat-footed 15
Hit Dice: 5d8+5 (27 hp); DR: 15/silver
Fort +7, Ref +6, Will +7
Speed: Fly 30 ft. (perfect)
Space: 5 ft./5 ft.
Base Attack +5; Grapple +6
Attack: Tentacle +6 melee
Full Attack: Tentacle +6 melee
Damage: Tentacle 1d6+1
Special Attacks/Actions:
Abilities: Str 12, Dex 14, Con 12, Int 5, Wis 13, Cha 15
Special Qualities: Shape change, poison immunity, silver vulnerability, fast healing 3, SR 15
Feats: Blind-fight; Combat Expertise; Great Fortitude; Iron Will
Skills: Bluff+10, Diplomacy +14, Disguise +10, Intimidate +12, Knowledge (any two) +10, Listen +9, Search +10, Sense Motive +9, and Spot +9
Advancement: By character class
Climate/Terrain: Any land and underground
Organization: Solitary
Treasure/Possessions: Standard

Source: Monster Compendium: Monsters of Faerûn

Alternate Form (Su): Malaugryms can assume the form of any creature less than deity status or a single object, as the shape change spell cast by a 20th-level sorcerer. When assuming the form of a humanoid creature, a malaugrym's physical ability scores (Strength, Dexterity, and Constitution) are the same as in its natural form, not the average scores for a member of that race. In any form, a malaugrym's true identity can be guessed by the golden light that glimmers in its eyes. A Spot check (DC 21) is required to notice this telltale gleam.

Silver Vulnerability (Ex): Silver weapons inflict the maximum possible damage against malaugryms. A malaugrym cannot heal damage caused by silver weapons naturally, including with its fast healing ability. Cure wounds spells and other magic heals this damage normally.

Spell Resistance (Ex): A malaugrym's spell resistance increases by 1 for every character level it gains.

Skills: When using alternate form, a malaugrym receives a +10 circumstance bonus to Disguise checks, as with the shape change spell.

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.

Shapechanger Subtype

A shapechanger has the supernatural ability to assume one or more alternate forms. Many magical effects allow some kind of shape shifting, and not every creature that can change shapes has the shapechanger subtype.

Traits: A shapechanger possesses the following traits (unless otherwise noted in a creature's entry).