Nilshai (CR 7)

Medium Aberration
Alignment: Usually lawful evil
Initiative: +6 (+2 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., Listen +13, and Spot +13

AC: 17 (+2 Dex, +5 natural), touch 12, flat-footed 15
Hit Dice: 8d8 (36 hp); DR: 10/magic
Fort +4, Ref +4, Will +6
Speed: 30 ft., fly 50 ft. (average)
Space: 5 ft./5 ft.
Base Attack +6; Grapple +7
Attack: Slam +7 melee
Full Attack: 3 slams +7 melee
Damage: Slam 1d4+1
Special Attacks/Actions: Spells
Abilities: Str 12, Dex 15, Con 10, Int 15, Wis 10, Cha 17
Special Qualities: ethereal jaunt, fearsome celerity, mind blank
Feats: Combat Casting; Great Fortitude; Improved Initiative
Skills: Concentration +11, Knowledge (arcana) +8, Listen +13, Spot +13, and Use Magic Device +13
Advancement: By character class
Climate/Terrain: Any land and underground (Ethereal Plane)
Organization: Solitary or infestation (2-4 nilshais plus 3-6 ethereal marauders)
Treasure/Possessions: Double standard

Source: Unapproachable East

Spells: A nilshai casts spells as an 8th-level sorcerer. The save DC for its spells is 13 + spell level. A typical nilshai spell list follows (spells per day 6/7/7/6/3): 0 - daze, detect magic, disrupt undead, light, mage hand, ray of frost, read magic, resistance; 1st - color spray, mage armor, magic missile, silent image, true strike; 2nd - mirror image, resist elements, Snilloc's snowball swarm; 3rd - dispel magic, lightning bolt; 4th - enervation.

Ethereal Jaunt (Su): A nilshai can shift from the Ethereal to the Material Plane as a free action and shift back again as a move-equivalent action (or as part of a move-equivalent action). The ability is otherwise identical with ethereal jaunt cast by a 15th-level sorcerer.

Fearsome Celerity (Ex): The nilshai's trilateral symmetry and alien mind allow it to divide its attention among multiple tasks at the same time. A nilshai gains an extra partial action each round, during which it typically casts a second spell or activates a magic item after it moves and attacks or casts a spell.

Mind Blank (Su): Nilshais are magically resistant to spells and effects of detection and mental influence. They are protected by a mind blank effect at all times.

Skills: Due to their ability to multitask and their trilateral symmetry, nilshais receive a +4 racial bonus on Listen, Spot, and Use Magic Device checks.

A nilshai is a stranger to the Material Plane and is almost always on a mission when encountered. It may be in search of a magic item, spying on local residents, or looking for intelligent humanoid slaves to carry off to its alien home. Whatever its purpose, it brooks no interference from denizens of the Material Plane. It uses its spells profligately, figuring that any threat deserves the quickest possible death. A common tactic against magic-using foes is to cast a spell and then ready a dispel magic to counterspell in the same round.