Langolier (3.5e Monster)

''Behind you the buzzsaw noise gets louder and louder, until suddenly it bursts through the floor leaving a circular tunnel through the earth. If a beholder was all teeth instead of eyes, it might come close to the horrible beast before you. Around its body-wide three-jawed mouth rippled silver teeth which moved erratically like some sort of organic chainsaw. It sees you, and it knows you don't belong...''

It is said that when paradoxes and time travel occur, a scar is formed in the timeline, ejecting a timeline unwanted, a yesterday gone that was once today. As the errant timeline sinks into the temporal plane, strange scavengers appear whose job is to consume the timeline itself and all in it. They are the langoliers.

The true form of the langoliers are not known, appearing as a sphere of mottled alien skin whose hollow body is parted by a threefold symetrical jaw filled with silver teeth that roar and move as if they were chainsaw blades. Within the very center of the langolier is a tiny singularity which takes the torn-up matter and sucks it away to god knows where. There is no sign of sensory organs and indeed the shape, alien movement, and the face they often come in groups seems to suggest they are but fingers of some larger extradimensional predator. Cutting through the countryside in chaotic and bizaare patterns, they consume the world until the very fabric of reality destabilizes and tears apart. Fortunately for us, langoliers are only found in the temporal plane and in forgotten timelines devoid of life... usually. Sometimes, when time travel, powerful chronological magic, and other effects are used, a rift in reality forms allowing others to enter a forgotten timeline or for the langoliers to exit.

Langoliers do not speak but are never quiet and never move silently, constantly making a horrible crackling some, like Rice Crispees after you pour in the milk. Disturbingly enough they are intelligent and can understand Abyssal, Celestial, Infernal (and if playing Pathfinder, Aklo).

Combat
Langoliers can smell the chronological displacement of others, and it drives them into a murderous feeding frenzy. If it senses someone not in their correct timeline, or someone who has used powerful time magic in the last 24 hours, they will chase them relentlessly, prefering them to all others. Highly mobile, they dart around the battlefield at whatever angle they please, but are even more dangerous if spending time to consume you with a full attack. Defenses mean little to them, eventually everything is chewed through.

Death Throes : When slain, their body destabilizes and implodes on itself violently. All those in a 20 ft. radius must make a DC 21 Fortitude save, or be drawn into its square (or within 5 ft if otherwise impossible, save negates). Anyone within 5 ft of the langolier takes 9d6+15 damage, and disintergrates if reduced to 0 or below. The saving throw is Constitution based.

Devour Matter : Everything can be eaten, everything. Langoliers automatically ignore all hardness and damage reduction, except DR/-. In addition, they can take a full round action to move up to their move speed and devour anything in its path. Unattended objects (such as the ground) are disintergrated leaving a perfect round tunnel. Creatures and magic items get a Reflex save for half, DC 21, or take 9d6+15 damage. It may move through enemy creatures, but provokes attacks of opportunity for movement as normal. It can move in whatever path it wishes, but creatures can only be effected by Devour Matter once per round no matter how many times it was passed over.

Extradimensional : The langolier exists in many dimensions at once, and as such weapons and spells which affect more than one dimension are super effective. The langolier takes 50% more damage from ghost touch weapons, transdimensional metamagicked spells, and force damage. On the other hand, the langolier is treated as having both ghost touch weapons and armor, allowing it to devour offending ghosts and incorporeal creatures.

Temporal Aura :  In a 20 ft. radius from the langolier, time is distorted. The langolier is constantly under the effects of haste (which are built into the statistics above), while anyone who comes into range must make a Will save DC 18, or fall under a slow effect for as long as they remain within the aura. A successful sav renders you immune to the slow effect for 24 hours.

Time Tracker : A langolier can detect time-displaced creatures and creatures who have used powerful time magics (generally 6th level spells and up) as if using scent. This scent does not apply to anyone who does not fit these criteria.