D&D 5E Stabbing Satan: A Fool's Errand.

[Charlaquin]

The key to killing Asmodeus without upsetting the balance in the Blood War and allowing demons to destroy the rest of the multiverse is to replace him. Work together with Mephistopheles or Glasya or someone to install as the new Lord of the Ninth - someone who will hopefully be more aligned with your PCs values, and more importantly, will be in their debt for helping get them their new position

 

[MarkB]

The key to killing Asmodeus without upsetting the balance in the Blood War and allowing demons to destroy the rest of the multiverse is to replace him. Work together with Mephistopheles or Glasya or someone to install as the new Lord of the Ninth - someone who will hopefully be more aligned with your PCs values, and more importantly, will be in their debt for helping get them their new position

Nah, the key to not letting the demons get out of control is to kick their asses next.

 

[J-H]

For a fight, you want:
A place - where is Azzy most vulnerable, and how do you bait him to go there? He's smart, so he'll know it's a trap, but he's arrogant.
A time - Maybe some allies? A diversion somewhere that draws away some of his guards or allies?
A tool - I assume he's immune to most normal weapons. He's not going to go down to typical spells either...his reserve of power is just too great. It's like fighting the BBEG from Worm - a straight fight does nothing, he can last longer than anyone else. It could be a sword, or an epic level spell or ritual, or a poison made from the willingly given blood of the lords of the 8 other circles, or _________.
A weakness - Where are you putting that tool to use?

For not a fight, you want:
A philosophy - How is the party different? What are they using to attack him that nobody has ever used before? How can you target not just his body, but his belief and spirit? What idea could break him or cause him to give up? This may need to be something that completely subverts the expectations of a final boss battle. Maybe you can redeem him, or get him to quit in favor of someone more competent, or offer him "rest" via a ritual that kills him but seals off 1/3 of the Abyss, or something like that.
Example: In the Bible, Jesus doesn't show up with a sword and armor and duel Satan in an epic, mountain-rending swordfight. Instead, he humbly sacrifices himself so that all who believe in him are counted as clean and justified, despite their sin, and thus Satan has no power over them any more. Everyone, even his disciples, thought the kingdom of God would be a literal earthly kingdom, and expected him to kick out the Romans, because they were thinking on a purely material level. For something like this, killing one of the primary and most powerful figures, one who filled the Lucifer role of getting a bunch of angels(devas/whatever) to defect, a purely material solution should not work, and should indeed prove disappointing.

There was a story hour here a decade or so ago that dealt with philosophical/idea based approaches as well. I'm drawing a blank on the name, but it involved a Paladin trying to redeem a succubus and free her from Grazz't. I think he ended up partly succeeding and partly falling but also some of the gods quit or changed alignment, the rules for summoning in the material plane got changed, and they ended up in high epic levels.

They may need to make some Religion checks to start in the right direction. They may need to also take some sidequests to look up the History of Asmodeus (there are multiple stories, all partly true and partly lies, that he's given out) to try to figure out the real truth and what they may need to do. I'd include a trip to some Upper Planes to do research and maybe test out their arguments.

Of course, this all becomes less "D&D, roll d20 to hit" and more free-form....

Warning: This can get very complex. You don't have to figure out the solution; you just have to get your players thinking in the right general direction, and then if they come up with something that sounds really good, it Just Works. Let them unleash their creativity.

 

[Mort]

Asmodeus is a prisoner of the nine hells. Even if not physically, his duty to containing the denizens of hell ties him there, bound by some magic.

"Slaying" him frees him to become a different greater god. One not tied to the nine hells, or even necessarily this plane of existence.

So he's set the party up, just like Strahd did, to allow him to escape by killing his tie to the nine hells.

And at some point the stronger residents of hell become aware of this, and do not want Asmodeus freed from his duty. Nor may Asmodeus help the party accomplish this quest, as his magical duty prevents that as well.

I like this direction - but with an add on. Not all the stronger residents want Asmodeus in place. Quite a few will be of the "better to rule in hell..." Philosophy and will be only to0 glad to replace him.

As such this is a huge opportunity for serious intrigue - which seems helped by the fact that 3 of the 4 PCs likely have extremely good Charisma (they're charisma casters) and could thrive in that kind of environment. I'm not talking about intrigue within the party (unless they're into that sort of thing) but more that navigating the Hells can be much more about political force, alliances, etc then pure physical force.

 

[MarkB]

Another approach is to take inspiration from Terry Pratchett's book Eric, in which the Lord of Hell has buried the place in bureacracy, and he is 'defeated' by being shunted into an administrative role where he's kept so busy coming up with new edicts, procedures and standards that he doesn't notice that nobody's paying any attention to him anymore.

 

[Mort]

Another approach is to take inspiration from Terry Pratchett's book Eric, in which the Lord of Hell has buried the place in bureacracy, and he is 'defeated' by being shunted into an administrative role where he's kept so busy coming up with new edicts, procedures and standards that he doesn't notice that nobody's paying any attention to him anymore.

I just realized this is the ONE Terry Pratchett novel that, for what ever reason, I've never read!

Well there goes the rest of my day - thanks a lot!

 

[MarkB]

I just realized this is the ONE Terry Pratchett novel that, for what ever reason, I've never read!

Well there goes the rest of my day - thanks a lot!

It's a relatively short one, at least - originally released as a large book with plentiful Josh Kirby art spreads. It's a good one, though.

 

[Mistwell]

I like this direction - but with an add on. Not all the stronger residents want Asmodeus in place. Quite a few will be of the "better to rule in hell..." Philosophy and will be only to0 glad to replace him.

As such this is a huge opportunity for serious intrigue - which seems helped by the fact that 3 of the 4 PCs likely have extremely good Charisma (they're charisma casters) and could thrive in that kind of environment. I'm not talking about intrigue within the party (unless they're into that sort of thing) but more that navigating the Hells can be much more about political force, alliances, etc then pure physical force.

Yeah good tweak Mort! I'd happily play in that game.

 

[Stormonu]

My thoughts turn a sort of scenario of Sauron and the rings. Asmodeus has something - influence or perhaps an artifact that grants him leverage over his lessers. Defeating big A may involving overturning the contract/allegiance/power/item of each of the lesser lords, in effect isolating big A and bringing his power down to something the PCs can manage. The final confrontation might be combination of uprising, combat and abjuration of big A and his works that in combination lead to finally overcoming - perhaps something like the final showdown with Pennywise from the recent IT movies?

There’s a Netflix series, done by the creator of Aeon Flux and using the storyline of Dante’s Inferno. I forget the name of it, but it could provide some very promising ideas, as D&D’s Hell, is essentially based on Dante’s works.

 

[Unwise]

I think it should become clear to them that they simply don't have the power to defeat Asmodeus themselves. The thing is though, they can comparatively easily turn the other lords against him, they could steal his rod of rulership, allow the demons to invade the hells, make his rivals think he is about to move against them, steal the taxes the other lords pay him - making him turn on them.

I'd make it so it had to be a series of clever grifts on their part to weaken his power. Once he is no longer the lord of the nine hells, then he loses a lot of his power and he gets a stat block.

Alternatively, looking at 4e lore (not sure if it is universal) they could find a way to fix the divine weave so that souls don't get delivered to the hells. They could change Avernus so that outsiders/outcasts (people that can't enter divine realms, forget the term) cannot go there. That would erode his powerbase and his underlings faith in him.