Doppelganger, Ethereal (CR 15)

Medium Monstrous Humanoid (Shapechanger)
Alignment: Usually lawful evil
Initiative: +5 (+1 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., Listen +13, and Spot +16
Languages: Common, Infernal, and at least one elemental language (Auran, Aquan, Ignan, or Terran)

AC: 14 (+1 Dex, +3 natural), touch 11, flat-footed 13
Hit Dice: 20d8 (90 hp); DR: 10/magic, piercing
Fort +6, Ref +13, Will +13
Speed: 30 ft.
Space: 5 ft./5 ft.
Base Attack +20; Grapple +19
Attack: Claw +21 melee
Full Attack: 2 claws +21 melee
Damage: Claw 1d4-1
Special Attacks/Actions: Assume identity, brain lock, mind wipe
Abilities: Str 8, Dex 13, Con 10, Int 14, Wis 13, Cha 15
Special Qualities: healing 8, plane shift, SR 20
Feats: Alertness; Blind-fight; Dodge; Combat Expertise; Improved Initiative; Mobility; Weapon Finesse
Skills: Bluff +14, Diplomacy +17, Disguise +27, Intimidate +16, Listen +13, Sense Motive +12, and Spot +16
Advancement: By character class
Climate/Terrain: Any land or underground
Organization: Solitary or squad (1 plus 4-16 jann)
Treasure/Possessions: Standard

Source: Monster Manual II

Assume Identity (Su): An ethereal doppelganger can absorb another creature's mind, memories, and personality. This process requires 1 hour of unbroken physical contact per level or Hit Die of the subject. The target may attempt a Will save (DC 22); if that is successful, the process is negated and the ethereal doppelganger must begin again. A willing creature can choose to waive the saving throw. After consuming the target creature's identity, the ethereal doppelganger can assume its form with 100% accuracy.

The doppelganger possesses the other creature's memo plus its alignment and all of its abilities, except for cleric spells of 2nd level or higher, a paladin's special abilities, other powers granted by deities. (This does not deprive subject of those memories or abilities; it only duplicates them in the ethereal doppelganger.) The doppelganger retains its own damage resistance, darkvision, fast healing, and spell resistance in its new form.

If an ethereal doppelganger commits an act that runs counter to its new identity's alignment, it is immediately forced back into its natural form for 1d10 rounds. It still retains the basic memories of the assumed identity, though not the deeper memories. If the subject dies before the contract is complete, the ethereal doppelganger immediately reverts to its natural form and loses all of that subject's memories and abilities.

Brain Lock (Su): As a standard action, an ethereal doppelganger can lock away the higher mind of an opponent up to 300 feet away, provided both are on the same plane and the doppelganger has line of sight to its subject. A successful Will save (DC 22) negates the attempt; failure leaves the subject mentally paralyzed. A brain-locked creature is not stunned, so attackers get no special advantage against it. Furthermore, it can still defend itself against attacks (its Dexterity bonus to AC, if any, still applies), but it cannot move or initiate any actions. A brain lock can negate various forms of special movement and thereby cause harm to the creature. For example, a brain-locked flying creature falls because it cannot flap its wings and a brain-locked swimming creature may drown because it can no longer move its limbs. The effect lasts 20 rounds, but it can be dismissed earlier.

Mind Wipe (Su): With any successful melee touch attack, an ethereal doppelganger can wipe all memory of its existence from an opponent's mind (no saving throw).

Fast Healing (Ex): An ethereal doppelganger regains lost hit points at the rate of 3 per round. Fast healing does not restore hit points lost from starvation, thirst, or suffocation and it does not allow the ethereal doppelganger to regrow or reattach lost body parts.

Plane shift (Sp): An ethereal doppelganger can use plane shift (caster level 20th; Will save DC 17) at will.

When it plans an extended stay on the Material Plane, an ethereal doppelganger uses its brain lock ability to render a chosen subject helpless, then takes that creature back to its floating home on the Ethereal Plane. In its sanctum, the doppelganger makes the subject comfortable and offers a deal. If the subject allows the doppelganger to assume his or her identity and acquire the desired item, the doppelganger will ensure the subject's comfort in the interim and return him or her unharmed to any desired location on the Material Plane afterward. If the subject refuses, the doppelganger wipes any memory of itself from the subject's mind, returns the creature to the Material Plane, and tries again with a new subject. Should the subject agree to the deal and then attempt to escape, the doppelganger sells him or her into extraplanar slavery. But if the subject accepts the agreement and complies with its terms, the doppelganger is as good as its word.

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).