A vasuthant is a monstrous and evil undead thing that resembles an orb of dark shadow with strange powers to drain light, life, and strength and to manipulate time, gravity, and reality itself. The most mighty and terrible of them is known as a horrific vasuthant.
A vasuthant takes the form of an orb of darkness or shadow, growing bigger and blacker and more powerful as it absorbs more and more life energy from its victims. A vasuthant begins only 2 feet (0.6 meters) wide and is but a shadowy cloud with an opaque core. These can grow to 15 feet (4.5 meters) in diameter. After this, they become horrific vasuthants, and can keep growing to 30 feet (9.1 meters) wide, appearing as utterly black spheres of nothingness. At all sizes, they are completely weightless. From the ball emerge black tendrils with which they grasp their victims.
A vasuthant can fly with perfect maneuverability.
A vasuthant wants nothing more than to devour the positive energy of any living creature unfortunate enough to come across it. After centuries of this, they swell to larger forms and even become horrific vasuthants, with greater powers. They operate alone, collect no treasure, and speak no languages.
A vasuthant always tries to whack a living creature with one of its tendrils. If it hits, it can easily grab hold and then try to drag its victim into its center, where it can then crush and enervate it. It can grab one creature of its size, or multiple creatures of smaller sizes, and horrific vasuthants can strike with two tendrils at a time. They can fly past their targets as they attack.
Any living creature caught inside a vasuthant will over time be physically crushed and enervated, its strength sapped by negative energy. In turn, the vasuthant is healed of any damage suffered, or even bolstered for ten minutes if it is already whole. Those trapped within are crushed or enervated until slain. Up to four creatures can be assaulted in this way at a time.
With some control of the forces of time and reality, a vasuthant can distort reality to alter the outcomes of events, potentially turning its failure into a success or an enemy's success into a failure. They can do this thrice a day, and a horrific vasuthant as often as it likes, but no more than once every several seconds. Furthermore, a horrific vasuthant can even open a rift in time to alter the past: time unwinds for several seconds, all events are undone, and the vasuthant acts again, able to try a different course of action to get a more desirable outcome.
In addition, a horrific vasuthant has magical powers to levitate or slow opponents, use telekinesis or reverse gravity, and emit waves of fatigue and waves of exhaustion, each a few times a day. It can even, once a day each, briefly stop time for itself or place a foe into a permanent temporal stasis.
A vasuthant absorbs and traps light, whether magical or natural, creating a dim, shadowy emanation to 60 feet (18 meters) from it, and twice this for a horrific vasuthant. This suppresses local light sources but it is not impenetrable to low-light vision and darkvision. Thanks to this, unlike most undead, all vasuthants are immune to harmful light; spells of light and the Sun domain don't bother them.
With an unholy toughness, a vasuthant is more robust than an equivalent undead creature and withstands efforts to turn undead and the like more stubbornly. It is also increasingly resistant to fire and electricity and utterly impervious to acid and cold. Horrific vasuthants shrug off all but the most devastating damage inflicted by mundane weaponry.
Vasuthants are native to the plane of Mabar, the Endless Night. On Eberron, they may haunt ancient dungeons, lurking near treasure to ambush and drain the life energy of those who venture in to claim it.