Vasuthant (CR 2)

Small Undead
Alignment: Always chaotic evil
Initiative: +3 (Dex); Senses: blindsight, darkvision 60 ft., Listen +4, and Spot +5
Languages: No language

AC: 17 (+1 size, +3 Dex, +3 natural), touch 14, flat-footed 14
Hit Dice: 2d12+4 (17 hp)
Fort +0, Ref +3, Will +4
Speed: Fly 30 ft. (perfect)
Space: 5 ft./5 ft.
Base Attack +1; Grapple +1
Attack: Slam +2 melee
Full Attack: Slam +2 melee and up to 4 enervating crushes
Damage: Slam 1d4, enervating crush 1d4 plus 1d4 Str
Special Attacks/Actions: Enervating crush, improved grab, reality distortion
Abilities: Str 10, Dex 16, Con -, Int 4, Wis 12, Cha 14
Special Qualities: +2 turn resistance, immunity to acid and cold, immunity to light, resistance to fire 5 and electricity 5, trap light, undead traits, unholy toughness
Feats: Flyby Attack; Improved Grapple
Skills: Hide +9*, Listen +4, and Spot +5
Advancement: 3-5 HD (Small); 6-9 HD (Medium); 10-16 HD (large); 17-25 HD (Huge); 26-34 HD (Gargantuan); 35-48 HD
Climate/Terrain: Any
Organization: Solitary
Treasure: None

Source: Monster Manual III

A spherical cloud of impenetrable darkness floats toward you. As it draws near, black tendrils reach out from the cloud's opaque core.

Vasuthants are shadowy, undead abominations. These life-hungry creatures vary greatly in size and power, each one growing larger as it sucks in more life energy. Smaller vasuthants appear as shadowy clouds, while larger varieties are colossal spheres of pitch-black nothingness that can suck up nearby light, sap strength, and manipulate gravity and time. Vasuthants possess immunity or resistance to most forms of energy.

A Small vasuthant is about 2 feet in diameter. As it advances in Hit Dice and becomes larger, its diameter increases to 5 feet at Medium size, 10 feet at large size, 15 feet at Huge size, 20 feet at Gargantuan size, and 30 feet at Colossal size. Vasuthants are weightless and know no languages.