So, I've reached a little conundrum. I want to include a Death Cult in a future campaign, however not all is as it seems with this particular group, as they secretly follow one of the Chaos gods. The only problem is, I'm not sure which god to align them to.

Khorne fits the blood-letting aspect of Death Cults, though I'm not sure the sneakiness is to his liking. Slaanesh is the most obvious one, striving for perfection in their swordsmanship etc, however that feels a little bit overdone unless someone can suggest a unique spin on it. Nurgle and Tzeentch don't seem to have any obvious connection, but the idea of a Tzeentchian Death Cult, one that uses the power of sorcery to boost their skill and speed whilst Tzeentch uses them in his plots is interesting. What are your thoughts and suggestions?

I'd say any Death Cult could be connected to any Chaos God - it just requires inserting their portfolio somehow, and to tweak the Death Cult's "look & feel" to suit their patron's culture. For example, for Slaanesh, perfection in sword fights might be one way, but savouring the act of killing (Countess Bathory) is another, as would be the taste of blood itself (autovampirism).

A Nurgle Death Cult might be concerned with introducing change (via decay) into a stagnant civilisation, specifically choosing their targets with the aim to disrupt stability. Perhaps they would not even kill their victims directly, but merely wound them using lethal, necrotic poison before withdrawing back into the shadows.

For a Tzeentchian Cult ... wasn't there a drug distilled from pulverised Psyker brains that would bestow temporary psychic powers upon the imbiber? I'd say you could easily structure a Death Cult just around this illegal substance!

I think this narcotic and its effects were mentioned in the Inquisitor's Handbook, though I'm not 100% sure. Might have been the Radical's Handbook, too.

I'd say any Death Cult could be connected to any Chaos God - it just requires inserting their portfolio somehow, and to tweak the Death Cult's "look & feel" to suit their patron's culture. For example, for Slaanesh, perfection in sword fights might be one way, but savouring the act of killing (Countess Bathory) is another, as would be the taste of blood itself (autovampirism).

A Nurgle Death Cult might be concerned with introducing change (via decay) into a stagnant civilisation, specifically choosing their targets with the aim to disrupt stability. Perhaps they would not even kill their victims directly, but merely wound them using lethal, necrotic poison before withdrawing back into the shadows.

For a Tzeentchian Cult ... wasn't there a drug distilled from pulverised Psyker brains that would bestow temporary psychic powers upon the imbiber? I'd say you could easily structure a Death Cult just around this illegal substance!

I think this narcotic and its effects were mentioned in the Inquisitor's Handbook, though I'm not 100% sure. Might have been the Radical's Handbook, too.

The blood one is quite interesting, and would be a very subtle hint, since a lot of Death Cults focus heavily on blood already

I like the idea of the poison a lot, would give me a good reason to include sieve-blades as well

You mean Spook? I've been interested in using that, though since it only grants Minor powers I've yet to see reason to use it for adversaries. However, a Tzeentchian death-cult would probably be able to get more powerful stuff, granting true discipline powers temporarily

Spook! Yes, I think that was it.

Do you even need more powerful stuff, though? I'd simply regard the Cult's reliance on this substance as a feature of their background description. Part of their culture, and the reason for their existence.

That being said, it could also deliver an easy explanation for a significant bonus to WS: Thanks to regularly taking this stuff, their fighters have an instinctual "feeling" of how their opponent would react to their attacks.

Also, something that just came to mind regarding Nurgle Death Cults: Plague Zombies. Do it.

Fair point. For true psychic/sorceous potential they'd probably have some specific people for that. The boosted WS is a nice idea, perhaps bonuses to dodge as well?

Oh god this campaign is going to be convoluted. A Tzeentchian chaos cult allied with a Death Cult, who are supported by Logicians in return for warp secrets and stolen goods, but the Logicians are actually being controlled by a Phaenonite who wants to unveil the Logicians in the Calixis sector to do away with a foe and distract the Inquisition whilst stealing the Logician research, whilst two noble houses have turned to Chaos in attempts to become the rulers of the planets, one family gone to Slaanesh whilst the other is more reliant on Nurgle and Khornate groups for power/to destabilise the current ruling family and oh no I've gone cross-eyed

Oh it gets worse. The 'forgotten' child of the family that has turned to Slaanesh remains loyal to the Emperor, yet unaware of her family's sins, and maintains her own guild of spies and assassins, however her mother's aspirations for her extend as far as the agreed-upon sacrifice to a Slaaneshi daemonette. Factoring in the politics of the planet, and the fact that a Shrine world playing host to a Sisters of Battle covenant is in the sector as well as a minor Forge World, with a strong Adeptus Mechancius presence on the planet, the proverbial defication is going to hit the fan at an appriciable percentage of the speed of light

Also, in regards to the plague zombies, that could be cool. The group I have at uni certainly has the firepower to survive such an encounter, though many of them would be worse for wear

I'm pretty sure your players will never sort through this mess If I was in your place, I'd simplify matters just a bit, but maybe your players are better at unraveling complex mysteries and like it that way. Interesting premise, in any case.

As for which Chaos God, I'd suggest a Slaanesh cult as Lynata offered, but one that is not made up of the run-of-the-mill debauchees. Instead, they could be a very cold and focused bunch of murderers, ritually cutting themselves off from every other weak human emotion save the extasy of taking lives, which kinda becomes their sole pleasure and purpose. Hunters for a religiously motivated hunter's thrill... They could be an order of master assassins, bit like a dark and twisted version of the Moritat. Which makes them human and creepy at the same time, and serves as a disguise for the Chaos worshipping.

Hmm... sounds more like two different campaigns set in the same setting to me though... one dealing with the Death Cult, the Logicians and the Phaenonite and the other one dealing with the struggle for power on that planet... not saying that's bad, in fact it might be quite interesting with the players having to decide which conflict to deal with... do they resolve one fully? Or will they split their resources ultimately failing both challenges?

Maybe you can think about making one of the campaigns some sort of Meta-Plot, which just happens and resolves (or not) depending on the player's actions. But, yeah, as Lone Pilgrim said, prepare for a lot of work going to waste on a convulted plot like this

Edit: Not saying I don't like it though

The idea behind the setting is the capacity for multiple campaigns, taking on one group at a time whilst having to make use of local connections to keep tabs on what the other identified groups are doing. At present I'm leaning more towards a Slaaneshi Death Cult, it could be very interesting, especially given the potential connection to the family who has fallen to Slaanesh, and friction with the 'forgotten' daughter's own guild of assassins etc

Please be so kind as to share your finished Death Cult with us - I'm sure everyone here would appreciate the inspiration

I'll be happy too. Won't be for a few weeks though, got exams to worry about before then