Yachlli - Multi headed Parasite Of The Outer Gods

Is it that by its indefiniteness it shadows forth the heartless voids and immensities of the universe, and thus stabs us from behind with the thought of annihilation, when beholding the white depths of the milky way?

There are things that float between the spaces of  The Outer Void that some can be called down on enemies by those who know how to use the super science of  the Eldar Things. Worlds have been make uninhabitable by these biological weapons. Yet these things are merely the parasites that inhabit the scales & slime of the Outer Gods. There have been instances of hyperspace gates opening up & these things pouring out. Hordes of these things then go rampaging across the planet's surface. Far worse then the D'Holes & the myriad of lesser races that also accompany the Outer God's orbits. There is now a standing reward for the destruction of these dark spawn among the floating reverse stars of hyperspace.  They thread their way among the demi spaces looking for any opening. There are now entire companies devoted to tracing the origins of  these monsters. 
There is a definite sequence of events to the appearance of one or more

1. The sighting of a purple sickly star in the sky often accompanied by strange weather such as ball lightning 
2. Still births in the area of the effected where the landing will occur.
3. Strange signs - random objects forming elder signs in fields, magnetic disturbances at irregular intervals, 
4. The black trace of light that often forms before the opening of a hyperspace gate way. This is often planet side 
5. Chanting from no known source 
6. The weather turning bitterly cold
7. Arrival of  The Yachlli
8. The invading force of aliens which summoned the creatures in the first place. 

The mechanism for the summoning of one or more of these things is unknown but its rumored to be a psychic tool into & of itself. The atomic structure & formula for the Yachlli is said to be such that no one being can contain it & it must be spread among 7 students. The teaching of the formula is said to ruin the mind of any sane being. 
 The life cycle of this being begins within the gut of an Outer God & is passed from these outer planar beings with some regularity. There are charts available upon the black market for such things. 
  Possession of knowledge of the Yachlli formula is a class 9 felony on most worlds of the 3rd Human Empire which will result in atomic cleansing. There are other rumors which tell of the planet crackers & torpedoes that have been developed are for the destruction of these very creatures. 
   If caught in the embryonic state the thing may be killed before consuming the massive quantities that it needs to evolve to its larger states of destructiveness. Only the most foolhardy of souls should engage this creature. The stats below are for the embryonic state only. 

 No. Enc.: 1
Alignment:Inimical
Move: 120'(40’)
Armor Class: 7
Hit Dice: 6
Attacks: 1 to 4 depending upon head development
Damage: 1d8 (plus special)
Morale: 9

 Note that its special attack is actually the monster reacting to attacks made upon it. The game master should make changes where necessary to allow for the monster adapting to the violence being committed.  

  There have been rumors that Altar four may have held answers about the original use that the elder things might have put this creature too. Since the loss of the knowledge of  the Krell there have been only vague hints in the annals found on various outpost worlds. 

   The Fungi from Yuggoth may have knowledge about these biological weapons of mass destruction but they have only answered with an amused buzzing.  It is hoped that as more of the Krell ruins are found that a counter measure will be found.