- In some cases they do this simply to restore lost Chi and P.P.E..
it will usually "loot" the body of all available Chi and P.P.E.
I don't actually see a power or crunch-mechanic for doing this theft though. None of the four "natural abilities" seem to fit.
One glaring issue to me is that they're negative chi creatures and they're probably possessing positive chi creatures so you'd need to do some kind of conversion.
Given this, I was thinking maybe we should bend the "Magic Abilities: None" policy and borrow from Chi Magic to get a mechanism for this fluff?
Assuming that once you possess someone, the PPE/chi of the possessed body qualifies as "Self" (in addition to the PPE/chi of your natural form inhabiting it) ... a couple level 1 spells would do the job.
Pg 72 "Convert Chi to PPE" could replenish the spirit's lost PPE (it spent 1 possessing the body already, maybe more if it had to make multiple attempts) by drawing on the positive PPE of the possessed body instead of the negative chi of the spirit.
Pg 73 "Convert PPE to Chi" could draw on the PPE of the host body (plus any PPE created from the host body's positive chi: but you need to cast the followup spell within 30 seconds if it exceeded max capacity) to replenish negative chi of the spirit.
Would it seem about right to use these two spells to emulate the mechanics of what CPEs are supposed to be able to do?
This would be like a 'natural ability' though so they couldn't teach humans to cast these spells
Pg 69 says "The P.P.E. for Chi Magic cannot be drawn from any other living creature!" so this would require making an exception from the perspective that it's not necessarily an "other" living creature because when you're possessing a body you ARE that creature, in a sense?
