The Jarring Magic of Magic Jar

[Âmesang]

I know this topic has come up before; heck, I was reading some of the threads regarding it and elsewhere, but… I suppose I'm still curious, especially with regards to shadow demons.

Shadow demons, like night hags and a few other creatures that inhabit the Lower Planes, trade in souls. They use their magic jar ability to trap souls and sell or trade them to more powerful fiends.

Book of Vile Darkness, p.173
How does that work, though? At first I thought it might have been a quirk of the 3.0 version, but the only meaningful difference is that an "incorporeal creatures with the magic jar ability can use a handy, nearby object (not just a gem or crystal) as the magic jar." (Makes me wonder why that appeared to be removed from the 3.5 version.)

…so here's what came to mind:

The shadow demon uses magic jar and enters into an acceptable receptacle. Because the shadow demon is an outsider, its soul and body form a single unit, thus it leaves no empty body behind when it enters the magic jar.
If successful, its soul/body enters the target's body (the host), and the target's soul enters the magic jar.
It waits for magic jar's duration to end, which would enact the clause that "if the spell ends while you are in a host, you return to your body (or die, if it is out of range of your current position), and the soul in the magic jar returns to its body (or dies if it is out of range)."
…except the shadow demon has no body to return to, since the shadow demon never left its body in the first place, since its soul is its body. So, from one perspective:

Since its soul can't return to its body, its soul doesn't return to its body.
Since its soul doesn't return to its body, it never leaves the host's body.
Since it never leaves the host's body, presumably the host's soul is unable to return to its body.
Thus, the host's soul remains trapped within the magic jar… forever?
Of course now the shadow demon is still inside the host's body, so does it stay there until the host's body is killed, thus freeing itself, or could it free itself at any point… and if so, is that due to its incorporeality? Of course leaving the host reconstitutes its body, but does it actually "return to its body" and, even then, magic jar's effect has already ended; are the subjects even subservient to its effects anymore?

So then I began to wonder how a player character might make use of this; say, for example, an evil wizard with an imp familiar:

Cast magic jar using the share spells option; this assumes that two foci would be required, one for the caster and one for the familiar.
The imp successfully possesses a target, its soul/body entering the target's body while the target's soul enters the imp's magic jar. The caster is still in his own magic jar.
The caster shifts back to his own body, ending the magic jar spell. Since the imp has no body to return to, since its soul is its body, it remains in the host body and the host's soul remains inside of the imp's magic jar… forever? However since imps are not incorporeal, can it not escape the host's body except through "death?"
I want to say that the target's soul remains forever trapped because, otherwise, that would make "trading in souls" a rather inefficient form of barter. Granted, a shadow demon would have to bum around for 10 hours until its magic jar ends naturally since it lacks the (D)ismissible option.

Honestly this whole line of thinking began with me contemplating the "double magic jar" trick, only trying to keep a soul inside of the magic jar instead of trying to claim a new, permanent body:

Cast magic jar and enter the focus, then successfully strike a target, swapping places. The caster's soul is in the host's body and the host's soul is in the magic jar.
Cast a second magic jar using a different focus. The caster's soul is in the second magic jar, the host's soul is in the first magic jar, and both the caster's body and host's body are empty.
Successfully possess a second target, forcing its soul into the second magic jar. Dispel the first magic jar.
"If the spell ends while you are in a host, you return to your body (or die, if it is out of range of your current position), and the soul in the magic jar returns to its body (or dies if it is out of range)." "The" being the operative word; the caster ends the first magic jar, returning to his body and sending the first target back to his… but the second target is still inside the second magic jar since that spell is still active and it was only "the" magic jar of the first casting that was affected.
"As a standard action, you can shift freely from a host to the magic jar if within range, sending the trapped soul back to its body. The spell ends when you shift from the jar to your own body." Does the act of shifting have to be a willing action? If not, then would the act of being forcibly sent back, by dispelling the first magic jar, automatically end the second magic jar? Else if it does require a willing act, then being forced back into your body should not end the second magic jar.
Assuming the later is true, then you have a glitch; the only conditions mentioned when the spell ends is when the caster is either in a magic jar or in a host. If the caster is already in his own body when the spell ends, what happens? Does the second host's soul return to its body, or is it forever trapped in the second magic jar?
The question of what happens when you successfully target an outsider also comes to mind, since it wouldn't have a body to possess, but I'm going to stop here 'cause it's midnight and my eyesight and mind are both blurry and I'm not sure if I'm even making sense anymore (if I ever did at all). :smalltongue: This is what I get for trying to contemplate magic in the form of computer programming "if" statements.

[Cerefel]

I think it's more likely that the demon uses Magic Jar to enter a body and get the soul into a gem. After that the demon has 10ish hours to either sell the gem (and soul) to someone who can use the soul within that time limit, or find some way to keep the soul past the spell's duration.

[Segev]

Yeah, this sounds an awful lot like a "fluff power" that has no mechanical backing. It works if the DM decides it does, and in that case, how the DM decides it does.

[Âmesang]

Which is kind of what I was hoping to avoid; I'd rather exploit some sort of logic glitch, even if unique to a particular monster, than rely on DM fiat/Rule Zero. :smallfrown:

[Segev]

Well...

One way to do it would be to rely on it being "at will" and having no finite duration (which might still require DM fiat).

1) Magic jar into a random object that you plan to store the stolen soul in.
2) Take over the desired soul's body; this places the soul in your object, and you in control of the victim's body.
3) Use your spell-like ability again, without ending the first effect.
4) Possess something long enough to kill the now-comatose body-of-the-victim.
5) End the new magic jar instance; normally, this would kill you, but since you're a creature that takes your "body" with you as part of your soul, when you have nowhere to go, you instead reform normally.

With DM fiat, you could decide that they can just end the spell-like ability for themselves and exit the victim's body (reforming their own) while leaving them in the jar.

[Âmesang]

An alternative to the above outsider-type familiar idea is casting the magic jar, sharing it with the familiar by using two foci, then spending the next round returning to your body, which should end the spell for you, but keep the familiar's active (so long as it remains within five feet, such as keeping the foci in a spell component pouch).

So the familiar possesses a body, its own body and soul fully entering the host while the host's soul is inside of the magic jar, then the caster dispels the familiar's spell, and since the familiar can't reenter its own body (since it technically never left), it remains in the host's body while the host's soul remains in the magic jar. Then the familiar just bums around the host's body until the body's slain, or can just exit the body at-will, leaving the corpse there (or animate it?).

…but of course it still requires a fairly loose interpretation of the spell's mechanics. :smalltongue:

[Rijan_Sai]

…but of course it still requires a fairly loose interpretation of the spell's mechanics. :smalltongue:

Maybe, but it also sounds deliciously EVIL and also sounds exactly like the type of thing something with that ability would do... or at least try!

I must remember to look up the BoVD later!

[Âmesang]

I am just trying to find a mechanical explanation for how shadow demons utilize magic jar to collect souls, especially since a soul in a receptacle is only worth 200 gp on the open market while trap the soul/soul bind are considering more expensive (but easier?) to cast.

Also I figure creatures that trade in souls would like something a bit more "permanent" than one hour per caster level, even if it requires a programming logic loop hole… but then maybe that's why trap the soul/soul bind are so expensive. :smalltongue: