Mind Flayer, Ulitharid (CR 12)

Large Aberration
Alignment: Usually lawful evil
Initiative: +6 (+2 Dex, +4 Improved Initiative); Senses: Listen +8 and Spot +18
Languages: understands Common, telepathy 200 ft.

AC: 20 (-1 size, +2 Dex, +5 natural, +4 mage armor), touch 11, flat-footed 18
Hit Dice: 12d8+36 (90 hp)
Fort +7, Ref +6, Will +13
Speed: 30 ft.
Space: 10 ft./5 ft. (10 ft. with 2 long tentacles)
Base Attack +9; Grapple +16
Attack: Long tentacle +11 melee
Full Attack: 2 long tentacles +11 melee and 4 short tentacles +11 melee
Damage: Tentacles 1d8+3
Special Attacks/Actions: Extract, improved grab, mind blast, psionics
Abilities: Str 16, Dex 14, Con 16, Int 21, Wis 17, Cha 21
Special Qualities: SR 27
Feats: Combat Casting; Improved Initiative; Improved Natural Attack; Iron Will; Spell Penetration
Skills: Bluff +15, Concentration +18 (+22 casting defensively), Diplomacy +14, Disguise +5 (--7 acting in character), Hide +8, Intimidate +17, Knowledge (any) +15, Knowledge (any) --15, Listen +8, Move Silently +12, Sense Motive +8, and Spot +18
Advancement: By character class
Climate/Terrain: Underground
Organization: Solitary or court (1 ulitharid, 3-5 mind flayers, and 6-10 grimlocks)
Treasure/Possessions: Double standard

Source: Lords of Madness

Extract (Ex): An ulitharid that begins its turn with at least four tentacles attached and that makes a successful grapple check automatically extracts the opponent's brain, instantly killing that creature. This power is useless against constructs, elementals, oozes, plants, and undead. It is not instantly fatal to foes with multiple heads.

Improved Grab (Ex): To use this ability, an ulitharid must hit a Small, Medium, or Large creature with its tentacle attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold and attaches the tentacle to the opponent's head. An ulitharid can grab a Huge or larger creature only if it can somehow reach the foe's head. If an ulitharid begins its turn with at least one tentacle attached, it can try to attach its remaining tentacles with a single grapple check. The opponent can escape with a single successful grapple check or an Escape Artist check, but the ulitharid gets a +2 circumstance bonus on the check for every tentacle that was attached at the beginning of the opponent's turn.

Mind Blast (Sp): An ulitharid can discharge a devastating psionic attack in the form of a cone 60 feet long. Anyone caught in this cone must succeed on a DC 21 Will save or be stunned for 3d4 rounds. The save DC is Charisma-based. This ability is the equivalent of a 4th-level spell.

Psionics (Sp): At will - charm monster (DC 19), detect thoughts (DC 17), dimension door, levitate, mage armor (self only), plane shift, suggestion (DC 18); 1/day - dominate monster (DC 24), mass suggestion (DC 21). Caster level 12th. The save DCs are Charisma-based.

An ulitharid is a tremendously dangerous foe in combat, because its potent mental attacks are backed up by 10-foot reach and a grapple ability reflective of the creature's large size. An ulitharid can protect itself with psionic image armor (reflected in the statistics above), and it normally maintains this power at all times.