Malasynep Mindmage (CR 10)

Huge Aberration (Aquatic and Cold)
Alignment: Often chaotic evil
Initiative: +4 (Dex); Senses: darkvision 60 ft., heat sense, Spot +17, and listen +17
Languages: Aquan

AC: 19 (-2 size, +4 Dex, +7 natural), touch 12, flat-footed 17
Hit Dice: 8d8+51 plus 6d4+36 (138 hp)
Fort +12, Ref +10, Will +14
Speed: 10 ft., burrow 40 ft., swim 40 ft.
Space: 15 ft./10 ft.
Base Attack +9; Grapple +25
Attack: Bite +15 melee
Full Attack: Bite +15 melee and slam +10 melee
Damage: Bite 2d6+8, slam 1d6+4
Special Attacks/Actions: Improved grab, psi-like abilities, spells, swallow whole
Abilities: Str 27, Dex 18, Con 22, Int 17, Wis 16, Cha 23
Special Qualities: Amphibious, immunity to cold, vulnerability to fire
Feats: Combat Casting; Empower Spell; Great Fortitude; Lightning Reflexes; Toughness
Skills: Concentration +17, Intimidate +17, Knowedge (arcana) +12, Knowledge (any one) +14, Spellcraft +12, Spot +17, Swim +16, and listen +17
Advancement: By character class
Climate/Terrain: Cold aquatic
Organization: Solitary
Treasure/Possessions: Double standard

Source: Frostburn

This malasynep mindmage possesses all the abilities of the malasynep, but also casts spells as a 6th-level sorcerer.

Typical Sorcerer Spells Known (6/8/7/4 per day; caster level 6th): 0 - daze (DC 16), detect magic, ghost sound (DC 16), ray of frost (+11 ranged touch), read magic, resistance, touch of fatigue (+15 melee touch; DC 16); 1st - mage armor, ray of enfeeblement (+11 ranged touch), shivering touch (+15 melee touch), silent image; 2nd - resist energy, numbing sphere (DC 18); 3rd - lightning bolt (DC 19).

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.

Cold Subtype

A creature with the cold subtype has immunity to cold. It has vulnerability to fire, which means it takes half again as much (+50%) damage as normal from fire, regardless of whether a saving throw is allowed, or if the save is a success or failure.