A holy conscriptionist? Pressganging the dead for use in extra planar warfare? That's actually a REALLY cool idea. I could see them also aggressively getting promissory notes like Organ donor cards. When you die you'll fight the good fight!
Not sure what "kalashtar" is...
Yes. And I find it particularly ironic that these are undead holy conscriptionists. If we use the original flavor text, these guys weren't made by the gods for this purpose - they're damned souls being given a job offer - even by the good deities. But I was actually talking more about a military police function. They track down conscripted spirits that went AWOL. And if they bring in a spirit that wasn't already impressed.... well, it is now. And yes, the gods do use such promissory notes - Tannan's already done just that. Too bad they didn't mention that the pact also causes him to age faster - insuring that the gods can collect that much sooner.
Kalashtar is a race from the Eberron campaign setting. What they are can't be explained quickly, but I'll try. One of the planes of existence is made up of dream stuff. When people dream, their minds go to this plane and shape it. But deeper in lie the plane's true denizens. The dream world is cyclical, going through millennia-long phases of nightmarish or peaceful forms. Currently the nightmare form predominates, and so most of the denizens are evil. But a few are different - predecessors of the next age, which may not be long off. The good beings are persecuted and murdered; being immortal beings, they are reborn afterward - but usually in keeping with the current nightmarish form. These good quori fled to our world, making pacts with a group of people, who chose to share their mind and body with the refugees. They are now utterly sealed off from the dreamworld, safe from the nightmares - except for the influence they have in our world. Being immortal creatures, the refugees did not die out when their hosts died. Instead, their soul was divided among ancestry. So all descendants of the original host have a portion of the quori.
You know what? Quicker version: kalashtar are descendants of humans who chose to harbor refugee psychic beings. The psychic being's soul pervades the collective group, but does not exist as a complete second mind in any individual.