Mind-eating parasites.

Points 50
Body: 0
Speed: 0
Mind: 10-50
Soul: 10-50

In their larval form, these highly unpleasant astral entities resemble small white wasps with human skulls for heads and a gnashing maw of large, razor-sharp teeth. They aren’t all that dangerous until an adept gets a fumble on a magick roll or some occultist finds the ritual that supposedly latches one onto a human target, but what they do when they get inside a human host is very similar to what the larvae of certain breeds of wasp do to caterpillars: they’re laid inside the host, and then they eat their way out. The difference is that Egovores eat the minds, personalties and memories of their human victims, and then they become their victims. It can take a long time and the victim has at least a fair chance of resisting and getting the creature out of his system, but Egovores have all the persistance that goes along with a ferocious urge to survive, and eat.
What happens is that for every lunar month that a human being is host to an Egovore, he must make a successful check against his Mind or Soul stat (GM’s choice, but usually the one that’s lower) with the minimum roll being the creature’s corresponding stat. If the roll fails, he loses something – possibly a memory if he failed a Mind check, or an aspect of his personality if it was against his Soul. The Egovore hungrily gobbles these up, and its relevant stats go up by the amount that the victim failed the roll, while his stats go down by the same number of points. For example, if the victim has a Soul of 55 and rolls 60 for the check, he loses 5 points from his Soul stat and the Egovore’s stat increases by 5. If the victim fails to get the minimum roll, he loses a number of points equal to the amount that he missed it by. Therefore, a victim who has to beat the Egovore’s Mind stat of 30 and gets 25 loses 5 points. Eventually, if things continue to go the Egovore’s way, the victim will become a vegetable when one of his stats is reduced to 0, and that’s when the creature finishes off anything that’s left and takes his place. It has a carbon copy of the victim’s memory and personality, while the remaining fragment of the victim’s psyche is ejected incoherent and screaming into the astral plane. An Egovore that becomes its host can pass for him convincingly, but they’re still no more human than things like Unspeakable Servants and Nonentities, and a terrifying lack of moral values often reflects this.
There doesn’t appear to be any easy way to get rid of Egovores, although a victim has a big advantage if he knows what’s wriggling about inside his mind and is consciously resisting (most people just slip away without knowing a thing about it). If he has a clue (people with Aura Sight can often see Egovores), he can reverse the process and drain the Egovore’s stats for every successful Mind or Soul check, causing it to weaken while his stats go up for a single 24-hour period. However, knowing what’s happening is pretty freaky, and the realisation calls for a rank-6 Unnatural check. How would you feel if the very essence of your being was being eaten from the inside out?