Adventure plot idea

[No brains]

There's a Lich who is taking people into a cult and using their souls to fuel their phylactery. Somebody pays you to slay them, of course. As you go about the investigation, you learn that the people in the lich cult are all people who have promised their souls to devils for steep prices, helping their families and peoples in exchange for damnation. What the lich is doing is committing infernal soul fraud by destroying souls before they can be collected and used to create devils.

So it's up to the party to decide if the lich is the real threat, but now the party is in the crossfire of the lich, the devils, the people who the devils want their stuff back from, and also probably Mordenkainen's balance losers. Maybe a marut or two.

Does this sound like a fun foundation for an adventure or even a campaign?

[Anymage]

Sounds a little high level. Both in the literal sense (neither liches nor dealmaking devils are the sort of thing that low level PCs should make any serious tries at), and in the sense that it's rather abstract. How much can this setting feature really be used to inspire adventurers to go off adventuring?

There's also the question of what the cult members really gain for their part. Their souls still get painfully destroyed in order to fuel the lich. It might make sense in an infernal crapsack city where everybody has to literally sell their souls to survive, and feeding a lich is at least a way to go out giving a big middle finger to a creditor who's otherwise impossible to dodge. There probably aren't that many people with soul debts in a normal campaign, not enough to make for either a widespread cult or to make this a reliable feeding strategy. Most normal people aren't keen on making bargains that will end with their deaths and the annihilations of their souls, even if they would get cool infernal perks out of it. And if this sort of thing did start to catch on, devils would most likely pick up and refuse to make bargains with anybody who seems like they're trying to loophole out of it.

[Mud Puppy]

In short, yes!

This is one of those morally "gray" campaign ideas that highlight the fact that personal experience, beliefs, background, worldview, etc. help influence "right" and "wrong." I can see a party of 4 coming up with 4 very different "solutions" and some very interesting/difficult inter-party conversations about what they should do...

[MarkVIIIMarc]

I like it very much. As mentioned earlier you'll have to make sure its CR appropriate.

Also and very importantly, can you tie this in to your PC's back stories?

Lastly depending on your players you can put a feel good twist on any solution they come up with. Perhaps there is an evil banker in on it with the Lich. Or a neutral banker's evil daughter. See if a reason soo many ppl in this town are in debt pops up.

[No brains]

Sounds a little high level. Both in the literal sense (neither liches nor dealmaking devils are the sort of thing that low level PCs should make any serious tries at), and in the sense that it's rather abstract. How much can this setting feature really be used to inspire adventurers to go off adventuring?

There's also the question of what the cult members really gain for their part. Their souls still get painfully destroyed in order to fuel the lich. It might make sense in an infernal crapsack city where everybody has to literally sell their souls to survive, and feeding a lich is at least a way to go out giving a big middle finger to a creditor who's otherwise impossible to dodge. There probably aren't that many people with soul debts in a normal campaign, not enough to make for either a widespread cult or to make this a reliable feeding strategy. Most normal people aren't keen on making bargains that will end with their deaths and the annihilations of their souls, even if they would get cool infernal perks out of it. And if this sort of thing did start to catch on, devils would most likely pick up and refuse to make bargains with anybody who seems like they're trying to loophole out of it.

For adventure inspiration- I imagine that the world must be in a bad place if devil deals are common enough for a lich to create a fraud ring. Maybe a war or famine has ruined a civilization. Perhaps people adventure just because there isn't any wealth left where they are now.

The ruined civilization idea is also what could drive people to sacrifice their souls. If someone could sell their soul to save a family, they might do it. Though with it being eternal damnation and all, they might look for some way to spite the devils.

Also the economic depression in soul deals occurred to me and that might be the most 'high level' idea at work here. If the lich is able to get wide enough influence, the devils are going to lose a major resource. If the DM uses the Blood War, then that could mean a shift in cosmic balance. Not only are the devils getting hosed and overrun by demons, but every cosmic force loses access to the soul the lich destroyed. The soul trade is a dangerous pot to stir and I think that epic danger would grab PC interest.

Thank you Marc and Mud for your input as well. The flexiblity of choosing lich or devils as the villain seemed like a nice quirk to me. Also having the PCs and NPCs have mundane motivations like money and food that get affected indirectly by the devil deals is an excellent suggestion. A banker could back the devils since damnation still brings coin to the city. Also agents of another kingdom may back the lich when they decide no means are beneath crushing the prosperity of the ruined land.