Imagine an Aboleth sets up shop in a cistern below a dungeon and gets the local sentient monsters (lizardmen, toadmen, goblins, etc) to worship it. What would they benefit from this worship, other than not getting eaten and/or allying themselves with a powerful being? I’d love to have the “priests” of the Cult of the Tentacled Father to get something unique out of their worship (access to the Aboleth’s arcane knowledge? potions from his muck with unique effects? learning psychic powers?). Any ideas?
Well, I’d argue that they don’t really need to get something out of it- Real world theocracies generally don’t get tangible rewards. On the other hand, this is fantasy, so let’s have some fun!
Muck potions sound good, but that’s more of a niche thing.
I’d say probably the biggest thing an Aboleth could offer was knowledge- Not necessarily spellcasting knowledge, but just, you know, brainpower. It’s waaaay smarter than a lizardman, right? So if it says fish here, hunt here, kill this human, this one can be bargained with, that tribe is going to prosper. That’s the real reason why they’re going to be writing “ALL HAIL THE DEEP ONES” all the walls- Because quality of life improved in every measurable way.
I’d be half tempted to let the oldest aboleths power clerical spells, as I’ve considered doing for ancient dragons and the mightiest titans. Although that comes with some baggage for your setting’s cosmology.
A less disruptive idea I’ve been playing with is that all members of a cult get one extra spell (the same spell). Where “cultist” can mean a cleric, a wizard, or even a non-classed human all in the same organization. In this case, the priests and acolytes of the aboleth might all have the same single spell, say once a day, or 3/day in the aboleth’s sanctuary, but not necessarily any other clerical powers.
Then the priesthood proper could have other powers as well, but I think you’re on the right track with “access to the Aboleth’s arcane knowledge? potions from his muck with unique effects? learning psychic powers?” The answer is, yes, all of the above. 
Have you seen Space Age Sorcery? Its a free pdf of spells and side effects available from hereticwerks. I wouldn’t use the whole thing, parts are tech-oriented, but pieces of it would work for aboleth worshippers.
How about the aboleths essentially function as “high priests” for whatever Lovecraftian divine entity that actually grants the spells? I believe that’s how Cthulhu is often explained: he’s just an awesomely powerful alien who is the high priest of his race, and the humans that worship him are actually getting their powers from Azathoth and the other truly divine entities in the pantheon.
Alternatively, what’s to prevent the aboleths themselves from being minor divine entities? A sort of demon, perhaps.
I can do this.
Hang on a bit. ACKS spell points plus divine power plus XP value means I can figure out how many spells and magical effects a powerful monster can grant to their worshipers.
Sources
http://autarch.co/comment/12931#comment-12931
http://autarch.co/forums/house-rules/spell-points-acks
Spell Level: Cost in Spell Points to Deity
1st Level: 0.5
2nd Level: 1.5
3rd Level: 3
4th Level: 5
5th Level: 7.5
6th Level: 10.5
7th Level: 3500
8th Level: 4000
9th Level: 4500
Cleric Spell Points Per Level
1st 0
2nd 1
3rd 2
4th 5
5th 8
6th 25
7th 45
8th 60
9th 80
10th 95
11th 115
12th 130
13th 135
14th 160
A creature generates excess divine power each day equal to about 6% of their XP value. A cleric gets 10% of this, the deity gets the rest. Therefore, the deity gets 5.4% of worshiper’s XP value as divine power per day, or 37.8% per week. (I plan to round this to 40% per week, by the way).
When a creature is sacrificed, 80% of its divine power passes to the entity worshipped.
The aboleth in question can also kickstart the process by using its own power to generate worshipers at first. It can safely use 6% of its own XP value as divine power per day to grant spells.
I don’t know what an aboleth has for XPV, so I will use a venerable dragon, who has an XPV of 12,800. 6% of this is 768. The dragon needs to use 90 of these to power its own spells. Using the costs for divine power previously established, without any worshipers, the dragon can grant a pretty significant number of spells; enough to power 4.2 14th level clerics! (I’m applying the x10 factor here as transition, by the way. If I assume that the spell point table is not intended to be converted, and it actually costs 1 divine power to grant 10 spell points, then it would be enough to power 42 14th level clerics.)
So in summary, if you want to assume that this does not requre any special spark and that any creature of sufficient power can use its power to grant spells, dragons can do it without any problem. But what if you’ve got some random kobold who somehow managed to get worshiped? How easy is it to power spells based purely off worshipers? For these assumptions, when I say ‘worshiper’, I mean someone who is actively worshiping. If your domain morale or other assumptions define not every member of the society as a worshiper, multiply the population by the appropriate value.
I’m not actually sure if more powerful worshipers grant more divine power for worshiping. I like to assume that they do, but for this example, every worshiper is also a random kobold/normal man with an xp value of 5. The deity gets 37.8% of their XP value as divine power per week, which I will now round to 40%, or 2 divine power per worshiper per week.
Every worshiper can support 2 1st-level clerics in terms of spellcasting power. It takes 80 worshipers to support a single 14th level cleric. Our ACKS demographics table tells us that a second level character occurs at a frequency of 1 in 50; even if we assume that every one of these is a cleric, 50 worshipers is more than sufficient to power a 2nd level cleric. A 14th level character is one in ten million, which is clearly more than sufficient to power him.
In summary, I find that the math supports this working without any trouble. The divine power in no way acts as a limit on the clerical spells of worshipers; the demographics of leveled characters provide a much harsher limit. In fact, it’s so much easier to the point that you almost certainly want to have this require some kind of spark of the divine or an extremely high XPV monster to allow someone or something to gather divine power from being worshiped. But any being capable of gathering divine power for being worshiped is capable of powering the spells of its congregants, for any congregation that even thinks about following the demographics.
As far as interesting ideas, I’ve got nothing, but I’ve got math that shows you can do basically whatever you want with it and ACKS will support you 
Son of a…ctrl A when I used an already open file as a notepad and can’t edit 
If any passing admin is capable of and wants to delete the first half of that, it would be great. (It’s a writeup of me playing Domains at War intro battle against myself, which cuts off halfway through the battle because I haven’t bothered to finish writing it yet. For the curious, the Aurans won.)
Um…I’m not deleting that glorious, glorious, write-up until you finish it!
“Therefore, the deity gets 5.4% of worshiper’s XP value as divine power per day, or 37.8% per week. (I plan to round this to 40% per week, by the way).”
What about (37.8*4 = 151.2) 150% per month? That’s nice and simple to remember, particularly since if you have (as an example) 200 orcs worshiping something, the divine power gained monthly is equivalent to the experience for 300 orcs.
That sounds like a much better rounding. I also realized that I forgot to multiply the cleric’s spell points by 7 for weekly consumption, so let’s try this again.
A 5 XPV worshiper grants 7.5 divine power per month (at XPV * 150%). A 2nd-level cleric consumes 30 divine power per month. It will take 4 worshipers to power a 2nd level cleric for a month - which is still significantly fewer worshipers than the frequency of clerics.
A 14th level cleric requires 4800 divine power per month, or 640 worshipers. At a maximum of one per ten million, this remains easy.
So my numbers were a little off, but the summary remains the same; it’s easy for worshipers to power clerics, the hard part therefore must be a) finding the clerics and b) being able to store and redirect the divine power in the first place.
I’m liking this very much - maybe combine this with some cool magitech as well for the priest. Or have the Lizardmen renovate parts of the dungeon - PCs go in expecting a ruin inhabited by savages, and end up against well-organized civilized lizards in a semi-restored fortress!
Another way to do this - the Aboleth, being ancient, knows many Arcane formulae; so he teaches Lizardmen with an Arcane spark (maybe a smarter-than-average Lizardman?) how to cast spells, this way you’ll have a Lizard Wizard as a “priest” with surprising arcane spells (the PCs will expect a proper Cleric or Shaman after hearing of the High Lizard Priestess, and end up facing sleep/charm person/magic missile or maybe even fireball!
How about granting the powers aboleths grant already? Namely the ability to breath water. Maybe the Lizard Man Priesthood are varying levels of aquatic, with the amphibians being the intermediaries between the common rabble and the holy aquatic folk, and the aquatics in turn being the intermediaries between the Amphibians and their “God”. I picture a pseudo-catholic affair with a fish-lizard-thing jesus and an aboleth almighty. Their twisted equivalent of the holy ghost/spirit is the aboleth mucus cloud.
To really take this to fun heights I’d propose using troglodytes instead of lizard men, making them strange, pale, and glandular. like the pictures from here http://archive.wizards.com/Dnd/Article.aspx?x=dnd/4dreye/20120822.
I leave it to you to work out the aboleth/troglodyte eucharist and sacrament…
I love this! Church of the Deep Almighty. Maybe even make it a whole heretical cult! With human followers, even, maybe! The entire “walk on water” thing becomes walk underwater, and fish symbols predominate.
This might be a faction in my Barbarian Conqueror King: Swamp Rebels campaign.
Note that the “default” civilized Lizardman religion, the monotheistic worship of Ixchala (the mother goddess; Lawful) also has some Judeo-Christian elements in it, as well as Aztec ones: the Lizardmen were once slaves of the Serpentmen, until Ixchala has seeded Mother Telina with an egg, from which hatched Nyla (who later became the Prophetess). Servants of the Serpentmen murdered Nyla; filled with motherly rage and by Ixchala’s divine wrath, Telina walked all over the countryside, her dead daughter in her hands, calling for vengeance. And thus Ixchala heard Telina’s cry, and smote the Serpentmen; Telina herself became the first Priestess, leading a Lizardman rebellion to topple their former masters, eventually rising to such a power which allowed her to resurrect Neya, sacrificing her own life to fuel the ritual (as Neya was dead for several years by then). Thus Neya, brought back from the dead by motherly love and the blessing of Ixchala, became the Prophetess, leading her people to freedom and founding the religion. Now atop the pyramids of the Lizardmen, dinosaurs are sacrificed in honour of the One Goddess (Chaotic Lizardmen sacrifice the hearts of sentient beings to appease the various gods of the now-dead Serpentmen).
The Deep Heresy would claim that their ancient Aboleth is actually Ixchala, or maybe an avatar of her, and that their High Priestess is an incarnation of Neya, evident by the miraculous power to breath water for more than the usual Turn (Lizardmen can hold their breath for a full Turn), and grant that power to loyal followers. The most loyal become Skum… And Troglodytes also congregate to this cult.
Send in the Lizard Inquisition to burn the Heretics and sacrifice their hearts for the glory of Ixchala!
Awesome thread. My current play by post campaign is actually based upon the idea that aboleths and illithids created all the other humanoid races and were fought off in a massive slave uprising, leaving behind tons of ruins and ancient technology etc. Seems people are thinking along similar lines about these guys.
Your campaign sounds awesome! Care to elaborate?