What happens when a Demon Lord is killed?

[BlueWitch]

I'm talking about big dogs like Orcus or Demogorgon.

I know as DM you sort of get to make up what happens next, but is there any lore on what goes down?
Hasn't it happened before?

What do you guys think? I need some ideas for DMing the next session so I thought I'd ask around here.

Right now I feel like retaliation from zealous underlings is the first immediate threat. But since Demons are Chaotic Evil they might not care about loyalty and stuff.

[ViperMagnum357]

Well, according the the fiendish codexes, evil outsiders can normally only be permanently killed on their home plane, so let us assume that happens. There is some lore info that Kostchtchie has straight up killed a bunch of other Demon Lords, and that did not seem to do anything to the balance in the Abyss; so presumably it happens often enough that it is not a huge deal unless the one killed leaves a significant power void.

Working from that, we also have some lore on what happens when a Demon Lord is merely MIA: they seem to get replaced quickly, by underlings or chief rivals. When Grazz't was imprisoned by Iggwilv, his lieutenants took control of his layers and basically ran his empire into the ground. Conversely, when Zuggtmoy was trapped in the Temple of Elemental Evil, her layer was almost entirely consumed by her chief rival, Juiblex; presumably because she had no decent underlings to run things.

In the event of perma-death, retaliation would probably only happen with either fanatically loyal minions that survived, or someone muscling in and seeing the deposer as an immediate threat to consolidating power. Nature abhors a vacuum, and in that respect the Abyss seems no different. Big dogs going down for the long count would create enormous power vacuums, though it seems Demogorgon specifically, literally cannot be permanently killed as long as he remains the nominal top dog in the Abyss.

[PoeticallyPsyco]

Almost certainly chaos among the underlings as ambitious demons try to take a slice of the now unclaimed pie. You'll get big shots trying to completely claim the full authority the demon lord once held, and duking it out (literally and metaphorically) with every other big shot that had the same idea. Mid-power demons and small fry will be able to take advantage of the chaos to rise in the ranks, pursue grudges, and/or transfer loyalties, depending on their inclinations and the actions of the higher ranked demons above them. Other demon lords would also certainly get in on the action, or try to take advantage of the demon lords that were distracted by trying to get in on the action.

If you've read Girl Genius, it would be a lot like the chaos that happened during the Castle Heterodyne arc when Baron Gilgamesh was injured, presumed dead. Every aspiring spark tried to take over the empire ("The baron was dead. I had an unstoppable army of flying apes. The logical next step was obvious." Quoting from memory so that might not be exactly right), except for a few who recognized that everyone else would go for the whole empire and settled for a smaller section of it while everyone else was distracted. And most of the neighboring empires/countries started pressing the borders.

If you've read the Night Angel trilogy, it would be a lot like when the God-King died. His children descended into cold war and a web of alliances that often flared up into all too hot war, except in cases where one of them stood head and shoulders above the others to the point that they could just enforce their will (or more often simply kill every potential challenger and sort the rest out later). Side Note: I need to reread those books; they were really good. One of the darkest single settings I've ever seen, but also very firmly on the idealistic side of the cynicism/idealism spectrum. It's a weird mix, but it worked well.

[EndlessKng]

This has happened before. Orcus has been killed before, historically. He then came back as the undead lord Tenebrous until he reclaimed his place and nature and shed the disguise, which in turn became a binder's vestige. I am fuzzy on the rest of the details but if you look up Orcus' history it may provide some guidance.

Of course, being chaos entities, the results of a demon lord dying could vary from lord to lord. In that case, Orcus came back first as an undead, which fit his nature. But I suspect the rules about demon lord souls vary as much as the lords themselves.

[Elves]

On the one hand, not much, as the others have alluded to, just political rejiggering. But frankly I think that works better for the bureaucracy of Hell, where if you die you just get replaced. The Abyss is more weird and chaotic so I would go for some big, dramatic effects, like the landscape of the entire layer changing (the demon lord's citadel unfolds itself like a living creature or a puzzle box, slouches down and becomes integrated into the landscape as something else, the weather changes or the skies retract like an eyelid to reveal something else, when Demogorgon dies all the water in Abysm starts draining, or becomes poisoned with his blood and turns into a noxious sludge that withers the landscape, etc) or the demon lord transforming into something else (think the Nightwalker from Princess Mononoke).

[Gnaeus]

I agree with the above answers.

I would add that it isn’t impossible for even chaotic evil things to admire and like, even love one another. Probably less common among Demons than even other evil outsiders, but still they could have allies/lovers/dependents/tools who might seek revenge.

More common and worrying from the PC perspective would be revenge type actions with different motives. Other powerful creatures could come to view PCs as a threat, or a tool of an enemy and seek to destroy them as such. This could be further complicated by the actions of other third parties. (Your party killed Orcus? Demogorgon takes credit. Others see you as a tool of demogorgon .....) Still others might seek the reputation that comes from slaying a lord-slayer, or to use the PC deaths as justification to take control of resources belonging to the former lord. Especially if the PCs are knowingly or unknowingly carrying treasure looted from the fallen lord, or some remnant (like a domain) of their late enemy has attached itself to them.

[Biggus]

the landscape of the entire layer changing (the demon lord's citadel unfolds itself like a living creature or a puzzle box, slouches down and becomes integrated into the landscape as something else, the weather changes or the skies retract like an eyelid to reveal something else, when Demogorgon dies all the water in Abysm starts draining, or becomes poisoned with his blood and turns into a noxious sludge that withers the landscape, etc)

That's some pretty cool imagery there, I might have to steal some of it for my own games.

[The Viscount]

As mentioned, Orcus has returned from death before due to his necromantic associations, and would likely be able to do it again.
If it's another of the top ones, especially Demogorgon that went, I think one of the more interesting repercussions would be in the Blood War. At any given time I would expect a sizable chunk of a Demon Lord's forces are bound fighting the one or two biggest rivals they have. In the sudden power vacuum, once the dust clears from the closest Demon Lord grabbing what loyalty and territory they can, the now freed-up troops can move on the first layer of Baator. If the devils are unprepared for this it might result in them losing the first layer, and moving the fighting to Dis.
Alternatively, if the Demon Lords don't feel like moving on the devils, there might be a sudden increase in demonic activity as they cause havoc in the Material Plane.

[Sepultra]

If it's another of the top ones, especially Demogorgon that went, I think one of the more interesting repercussions would be in the Blood War. At any given time I would expect a sizable chunk of a Demon Lord's forces are bound fighting the one or two biggest rivals they have. In the sudden power vacuum, once the dust clears from the closest Demon Lord grabbing what loyalty and territory they can, the now freed-up troops can move on the first layer of Baator. If the devils are unprepared for this it might result in them losing the first layer, and moving the fighting to Dis.
This is a really interesting take, yeah. The other thing I could see coming from it would be the reverse: a huge relief for the devils as the demon lords dedicate more of their forces to getting their own rewards.
I wonder what Devils would do in such a situation, honestly.

[BlueWitch]

Thank you for the answers guys! It's been an interesting and eye opening read! Some of you thought of things I didn't even consider, so kudos for that. I think my "Imagination Level" increased!

[Asmotherion]

Since the layers of the Abyss are made to reflect the subconsious of the ruler i'd argue that Powerfull Demons may fight over dominion of a layer as soon as it's freed from it's previous ruler. Other Demon Lords may attempt to expand their domain wile maintaining their own and strong demons (Balors for example) may try to become Demon Lords. As soon as a new ruler is established the whole layer would change dramatically to match the new Ruler's will.

[Arcane_Secrets]

Some thoughts:

If the Demon Lord was killed by someone specifically and didn't die from other causes (which is much rarer but I'd say still happens/happened) then whoever defeated them purges the incorrectly-loyal, forces them to flee for their lives if they don't get killed immediately, and probably kills a bunch of who would otherwise switch loyalties just to show that they're vicious enough to be in charge.

There's also the issue of layer control (which is something I've been thinking a lot about for quite some time). If a layer's concept is strong enough even without that particular lord to keep going, then the layer or layers that it controls isn't guaranteed to change immediately after death although it might. Kiaransalee taking over Thanatos after Orcus died didn't stop it from being a layer of the undead.

I also think that in some cases, if a Demon Lord is really despised their dying probably starts wars amongst rivals who arrive to try and plunder their layer (which is what I think happened after Fraz 'Urb Luu got imprisoned) and fend off 'layer scavengers'; gangs of demons who want to use unclaimed or disputed layers to breed more of their particular kind, use it as a base for attacking worlds or the upper planes, so on), Juiblex who starts showing up, makes things even worse and more dilapidated/corroded, et cetera.

[Jowgen]

The Savage Tide adventure path addresses this in the case of Demogorgon.

Barring certain exceptions like Pazuzu, a Demon lord is a one who has gained control over an abyssal layer, not just by occupying it by military force, but actually establishing a specific kind of connection with it. This bond to the layer is a symbiotic one, wherein the Demonlord can shape the layer while the layer also shapes it.

The Nietzsche reference is a bit on the nose, I know.

When you kill a demon lord on his home layer, his essence disperses with varying degrees of permanency and the "crown" of the layer is now up for grabs. Anyone sufficiently powerful present can claim it and assume command of the layer. In the case of Demogorgon, the layer actually makes you grow a second head, forcing the same shtick demogorgon had. The essence of the demon lord might dissipate completely, be captured by someone present who has the right skillset/tools (Iggwilv does it in Demogorgon's case), or it might reform in some way elsewhere (as happened with Orcus).

However, considering the wide variety of the abyss, there is bound to be some variability. Some layers might actively want someone to have the crown and leave it for the taking, others might have other requirements for claiming rulership, like the sign of the smoking eye from the Shackled City adventure path. Most layers have never been claimed, which is likley at least in part due to the difficulty associated with the process. You'd think it would be easier to claim it if you kill the previous ruler, but said ruler might have altered the layer to make succession more difficult too (again, shackled city iirc).

Graz'zt is the only one who has managed to claim multiple layers afaik, and the result is significant blending between them (e.g. Azzagrat is a metropolis that exists on 3 layers in a weird overlap manner).

As for political ramifications, I think it has been reasonably well covered in this thread. Battle lines in the abyss will shift, some might rise in positions while others fall, but on the whole an equilibrium will be maintained; with the only real threat being loosing ground in the Blood War.

[liquidformat]

Almost certainly chaos among the underlings

So business as normal? I mean seriously this is the abyss we are talking about chaos is the natural state of things, nothing really changes that it just becomes a different type of chaos. Say a group of paladins murders their way in and kills off a lord and its top minions, you will simply have a power vacuum that explodes into a chaotic war for power and former rivals swarming in to take 'control'. but it wouldn't seem much different from normal in the chaos of the abyss..

[Eldan]

This has happened before. Orcus has been killed before, historically. He then came back as the undead lord Tenebrous until he reclaimed his place and nature and shed the disguise, which in turn became a binder's vestige. I am fuzzy on the rest of the details but if you look up Orcus' history it may provide some guidance.

Of course, being chaos entities, the results of a demon lord dying could vary from lord to lord. In that case, Orcus came back first as an undead, which fit his nature. But I suspect the rules about demon lord souls vary as much as the lords themselves.

That happened in the adventures The Great Modron March and Dead Gods, both for Planescape, by the way.

[GloatingSwine]

Almost certainly chaos among the underlings as ambitious demons try to take a slice of the now unclaimed pie. You'll get big shots trying to completely claim the full authority the demon lord once held, and duking it out (literally and metaphorically) with every other big shot that had the same idea. Mid-power demons and small fry will be able to take advantage of the chaos to rise in the ranks, pursue grudges, and/or transfer loyalties, depending on their inclinations and the actions of the higher ranked demons above them. Other demon lords would also certainly get in on the action, or try to take advantage of the demon lords that were distracted by trying to get in on the action.


Of course the side effect of that is a downward trend in demons troubling the prime material because they're all busy shanking each other.

And an upward trend in devils doing the same because hey, it's free real estate.