The Impellions were created by the Dark Primes to serve their high priests. They are very rare. One Impellion is a traditional reward for destroying a large town or city. They arrive in this world in the form of fist-sized eggs.
They devour whatever they can, and grow to their full size in minutes. They must eat large quantities of fresh prey to keep up their physical speed, slowing down somewhat if starved.
They are almost like machines in the execution of their assigned tasks. They do not like to talk to anyone but their master or mistress, and do not possess emotions such as pride, affection, or anger.
Their tails are equipped with heavy armor-piercing projectiles which they launch at their enemies. As soon as one is fired, a new one starts to form, and is ready a second later. Their scythe-claws can even cut through stone.
Except for the tips of their four feet, their bodies disintegrate nearly anything touching them. They possess a psionic ability to appear to be in a location that is not where they are. The more magic a viewer possesses, the more pronounced this effect. Impellions can magically see through total darkness but not walls, so they try to avoid being in buildings or other structures that impede their vision.
As if that was not enough to keep them alive, they are also the fastest self-regenerating creatures in all the Dragonlands. Because they require magic to live, they can not survive in the Olde World. It is fortunate that Impellions cannot breed, for they would quickly overrun the world if they did.
They can be targeted through sonar and other discriminatory senses. It is also possible to hazard a guess as to where they are, by watching the prints of their feet in sand, their shadows, and similar indirect indicators.
While Impellions are immune to magic and psionics that attempt to affect them (such as setting them afire or mind-control), they are not immune to indirect use of magic, such as setting a forest around them on fire or blowing at them with a gale-force wind.
Perhaps their greatest weakness is that they must obey the will of the one that awakened them. They are cunning but not geniuses; they rely on the wits of their superior. If that person is somehow removed, the Impellion will try to find a replacement patron on their own.
After they have been vanquished, Impellions are strangely forgotten, except by those who faced them directly in combat. Mage lore sometimes has scrolls with precious accounts of the encounter. The reader of such lore could learn that a magical circle blocking out all magical energy formed around an Impellion will cause it to revert back into the inert egg. To awaken it again, it must be bathed in the blood of a dying innocent Furre (a Wyrmme or Bugge will not suffice).