
Steve Greer Contributor |

James Jacobs explained this in detail in Fiendish Codex I: Hordes of the Abyss. Basically, the "soul" (IIRC) of the fiend returns to the Abyss/Nine Hells to start the process of climbing the fiendish ranks once again or perhaps some other fate. In the case of Demons, they are returned to the primal Chaos that constitutes the stuff that plane. I don't have the 2nd book in this series yet, so I can't say what happens to them back in The Nine.
As for the body left on the Material Plane, it basically decomposes at an extremely rapid rate. In my own games, I've always described their dead bodies as hissing, bubbling, and turning to goo and bones that quickly evaporate/turn to dust.

Crust |

I've never read the Fiendish Codex books, but I've always deemed that any demon/devil that is "summoned" using a summon monster or planar binding spell and then killed is immediately whisked back to the lower planes. Any demon/devil that has been gated in or that has physically stepped through a portal into the Prime is permanently destroyed/killed if brought to -10 on the Prime.

Thanis Kartaleon |

The short answer: They're dead.
Gate is either a creation or calling type conjuration spell. The creation function makes a portal that functions as a location-based plane shift. Plane shift is a teleportation type conjuration spell.
Creatures who are called actually die when they are killed; they do not disappear and reform, as do those brought by a summoning spell.
A teleportation spell transports one or more creatures or objects a great distance. The most powerful of these spells can cross planar boundaries. Unlike summoning spells, the transportation is (unless otherwise noted) one-way and not dispellable.
Essentially, calling and teleportation effects work the same way, the only difference being that calling is an effect that pulls a creature to the caster, while teleportation effects take the caster to a location.
Summoning, on the other hand, is pulling a "temporary" version of a creature to the caster. Any effects that are dealt to the temporary creature do not affect the actual creature.
TK
Incidentally... Trap the soul is a summoning effect...

Todd Stewart Contributor |

3e has given different answers to this over time.
Initially 3e said, ostensibly in the name of simplification, that summoned fiends went back to their home plane, but those who were called/gated/physically present were killed, dead, end of story. This was a wasteland of flavor however and pretty much sacrificed fluff and lore upon the alter of rules simplicity (and the SRD still reflects this).
Fiendish Codex I and II have gone back to the spirit of the more complex 2e exploration of the matter. Their essence returns to their home plane and slowly reforms, with the exact specifics of this process depending on the type of fiend and the power of the fiend. Least Tanar'ri might be purely dead while Balors might be momentarily inconvenianced for a short time, though they might lose some power in the process, or even become demoted down a caste.
Baatezu take a set number of years, and may be demoted by their superiors for having died.
Yugoloths have yet to be addressed specifically in 3e, but going by their 2e flavor text they'll reform on their home plane eventually, and some of them can only be killed permenantly on specific planes, or off of specific planes (they were rather complex).

The Jade |

gated fiends or others that arrive by non-summoning means leave a corpse behind.
Whereupon our crew at Greerjadeo Co. scoop up the remains, whisk them away to our factory in The Duchy of Goldblum, and through an arcane taxidermic process transform them into high priced pinatas stuffed with wrapped salt-water taffy for Ye Old Hammer-maker-Schlemer catalog (very big with the the dwarves).

Todd Stewart Contributor |

If a killed fiend leaves a corpse, I'll raise a question for everyone then because the plain-jane RAW don't consider the situation fully perhaps:
Fiends are beings of metaphysical, spiritual substance rather than true material creatures. They lack body/soul duality, and if killed and presumably their essence migrates back to the plane that birthed them... there isn't anything left to leave a dead fiend corpse behind now is there? Not a corpse in the conventional sense with any real link to them.
Kill a fiend and you might have a scorch mark left behind, or a puddle of acid that births hornets as it evaporates, but given that their soul -which by then is already on its way to the lower planes- is the same thing as their body, whatever is left behind isn't their true corpse. Whatever is left behind is, in my own perception of the matter, a manifestation of their death, a patch of the prime material sullied and physically warped and twisted by their passing. It's not a corpse, even if something looking like a corpse might on rare occasion be left at the scene of their death.
Your mileage may vary.

Jeremy Mac Donald |

If a killed fiend leaves a corpse, I'll raise a question for everyone then because the plain-jane RAW don't consider the situation fully perhaps:
Fiends are beings of metaphysical, spiritual substance rather than true material creatures. They lack body/soul duality, and if killed and presumably their essence migrates back to the plane that birthed them... there isn't anything left to leave a dead fiend corpse behind now is there? Not a corpse in the conventional sense with any real link to them.
Kill a fiend and you might have a scorch mark left behind, or a puddle of acid that births hornets as it evaporates, but given that their soul -which by then is already on its way to the lower planes- is the same thing as their body, whatever is left behind isn't their true corpse. Whatever is left behind is, in my own perception of the matter, a manifestation of their death, a patch of the prime material sullied and physically warped and twisted by their passing. It's not a corpse, even if something looking like a corpse might on rare occasion be left at the scene of their death.
Your mileage may vary.
It's not RAWs fault. Eric Mona and James Jacobs really need to start fast talking in order to explain this sort of thing. Essentially RAW made them of one essence both body and soul. So if they died when gated in they where permanently destroyed.
However James and Eric decided that their essence got transported back to the Abyss and that they simply could not die anywhere but in the Abyss. However they now seem to have some kind of a primal essence that can be called back to the Abyss that spawned them in the first place - in other words duality.
This in turn opens a whole other can of worms. Creatures from the Outer Planes can't be raised - they have no soul. Except now apparently they do have some kind of a soul or primal essence that moves from plane to plane. Or at least Demons and Devils do and if this is true of Fiends then it stands to reason that it is also true of Angels and other outsiders. Now if these creatures do have some kind of a primal essence - or soul if you will - then why can't they be resurrected?

KnightErrantJR |

It's not RAWs fault. Eric Mona and James Jacobs really need to start fast talking in order to explain this sort of thing. Essentially RAW made them of one essence both body and soul. So if they died when gated in they where permanently destroyed.However James and Eric decided that their essence got transported back to the Abyss and that they simply could not die anywhere but in the Abyss. However they now seem to have some kind of a primal essence that can be called back to the Abyss that spawned them in the first place - in other words duality.
This in turn opens a whole other can of worms. Creatures from the Outer Planes can't be raised - they have no soul. Except now apparently they do have some kind of a soul or primal essence that moves from plane to plane. Or at least Demons and Devils do and if this is true of Fiends then it stands to reason that it...
First off, they didn't really just decide this on their own. They returned to how fiends were portrayed for decades in D&D in previous editions. In a way, the "outsiders die because they are the same physically and spiritually" kind of felt like a dumbing down of how things work in the D&D cosmology.
I would rather there be consistancy in how thigns work "lore wise" as opposed to changing decades of lore because its a simpler way to explain things "rules wise." To me the rules exist to help tell a story, and when they start dictating that you change your older stories, you start running into problems.
Mortal beings have a physical side (their body) and a spiritual side (their soul). Outsiders are a physical manifestation of their own self, a solid body made out of soul stuff. If killed, most of this disperses, some of it might "do tricks," and the rest filters back to its plane of origin, and the personality of the fiend in question might or might not be powerful enough to remain "itself" when it arrives in its home plane, and if not, its "recycled."
If you kill a fiend in its home plane, its body and soul are one, and it just disperses, violently, into its home plane, and doesn't come back. I guess to me it makes as much sense as anything else in the game does. And it makes more sense than the laws the the universe changing to reflect a "new edition."

Steve Greer Contributor |

Steve--is what you're saying consistent with the Fiendish Codex stuff you reference above? I don't have those books. Thanks again.
Geekhick. Here is what James says ...If a demon is killed on another plane, its body eventually returns to the Abyss-unless trapped through magical means, such as by a dimensional anchor spell. (*See the Demonic Death Throes sidebar for more details on how demon bodies sometimes disappear.) No matter what happens to the demon's body, if it is killed outside the Abyss, its "essence" falls back into the raw chaos of the Abyss, where it is then reformed as a new demon.
There is more, but that should suffice.
*This sidebar supports my own way of dealing with dead demon corpses left behind on the Material plane. There is a d20 table you can use to randomly determine what happens to the body. One result happens to be nothing at all; it simply perishes the way a normal creature on the Material plane does. However, the rest is close to how I usually treat their deaths in my own games. The flavor text captures the feel of the table that follows. It goes "...and as the marilith's head fell from its shoulders, blood bubbled forth. Tiny grubs swam in the gore, and as we watched, they consumed the demon's body and attempted to crawl away to freedom. Revolted, we threw the stone table on the corpse, hoping to squash the foul creatures. Later, when we cleared away the broken stone, we found only the demon's swords and a spattering of black and red blood. The larvae were gone." --The Battle of Darkspur, as related in the Black Scrolls of Ahm
BTW, I suggest picking up Fiendish Codex I and II if you like using demons and devils. It's an excellent source of lore and adds great flavor to using them in your game.

Todd Stewart Contributor |

This in turn opens a whole other can of worms. Creatures from the Outer Planes can't be raised - they have no soul. Except now apparently they do have some kind of a soul or primal essence that moves from plane to plane. Or at least Demons and Devils do and if this is true of Fiends then it stands to reason that it...
KnightErrantJR pretty much made my reply for me on the first part of your last post. Erik and James did a nice job returning the flavor of fiend death to where it had always been before early 3e stripped it away.
And you can't raise a dead fiend/celestial/slaadi/etc because if they're permenantly killed their non-dualistic body/soul essence merges with their home plane. At that point they no longer exist as a distinct being seperate from their plane/alignment, so you can't easily gather up that digested (for lack of a better word) soulstuff and reform them.