Bluetspur I'd started on some time ago (in fact I posted most of the details in a thread some 4 years or so ago), but I figured I'd come back to it and touch it up after a couple years and a fresh look. I liked the details I'd worked out for the domain itself, but I'd never fully gotten into updating the darklord proper. So that's what I'm here for.
For some background, I'll have two spoilers below. The first details my general philosophy on how to handle darklords and their curses. The second is some background details on illithids to explain why I did this the way I did.
However, all who live near this section of the Balinoks knows the dangers of wandering its peaks and valleys. Those foolish enough to sleep within Bluetspur experience dark, horrifying dreams that provide little good rest and leave even the strongest and bravest shaken the following morning. But even the dreams are not the worst part of this domain, for it is said an unspeakable horror lurks within, something that no man should ever lay eyes upon, and that to do so twists the mind and body in terrible ways.
And in some ways, there is truth behind these tales and histories, for deep beneath the mountains lies the true heart of Bluetspur: the illithid city, the true Bluetspur (to surface dwellers, this stretch of land has many names, though some who have spent the night here do speak its true name, remnants of a dream).
The dark lord of Bluetspur is the leader of this illithid city: the Elder God-Brain.
Eons ago on a world now since long forgotten even by time itself, an illithid elder brain ruled a colony of illithids. While dealing with its duties, this elder brain still found plenty of time for devoting itself to pure thought and scheming. This was not in and of itself unusual (plotting is first, second, and third-nature to illithids after all), but this particular elder brain found itself pursuing a line of thought unique among its kind: it actually considered the possibility that the current illithid form was not, in fact, perfection. After all, it found itself reasoning, if psionic illithids were true perfection, then why had they not fully exterminated their magical cousins? And if they were not, thusly, truly perfect, would it be possible to achieve that true perfection?
Having found itself captivated by these new thoughts, the elder brain devoted centuries to considering their implications and then, eventually, ideas and plans on how to act on them.
Finally, the elder brain had decided on a course of action and set about its master plan. It ordered the illithids of its city to begin capturing creatures, not just as slaves and food, but for new experiments. The elder brain wished to test its theories out on lesser specimens before it graduated to experimenting on illithids themselves. The details of these experiments have been lost, and that is likely for the better. The luckiest 'patients' failed to survive them, with the unluckiest few surviving to become eldritch abominations, mindless and hungry and set loose by the elder brain, who no longer had need of them.
Soon, the elder brain surprised its minions with a new request: capture and bring to it magical illithids that it might experiment on them. And so began the elder brain's descent into true evil, for in its experiments it learned more about the secrets of magic, and the power of spells like polymorph, which seemed to transcend even its own psionic crafts(ftnt1). Thus it turned to its own population of illthids and began to subject them to experiments as well, seeking to find ways to merge the power of magic and psionics into a single being. Alas, it was never able to achieve this, but still its dark knowledge grew, and, finally, unable to resist the ultimate temptation, it committed itself to the series of actions that would curse it forever and draw Bluetspur into Ravenloft: the elder brain began ordering its minions to add other brains to its mass, starting with those of magical illithids, but soon even those of other races: drow, duergar, kua-toa, even captives of surface races such as humans.
No longer a mere, normal elder brain, it rechristened itself as the Elder God-Brain in its delusional exultation, not even realizing as the Dark Powers pulled its tunnels out of its home world and brought the entire colony to a new home. (ftnt2)
This leads into the current setting of Bluetspur: beneath the surface, the Elder God-Brain continues its experiments upon its own kin, shaping and changing portions of its population on its whims. Thus, the basic story of the Thoughts of Darkness adventure fit fully into the feel of this domain: creating vampire illithids is almost certainly something the Elder God-Brain would sanction and support. I also see other types of illithid abominations existing: alhoons, ullithids , and the illithid-ropers from the Illithiad, for starters. But I see others as well: in the waters off the coast of Bluetspur can be found small roaming gangs of illithids that have been mutated to live in the dark depths of the ocean.
And on the surface, sometimes experiments escape (most experiments that survive are just turned loose into the tunnels, as the brain has little use for them after their creation; it is after the knowledge after all), and roam the land, always as horrifying, mindless monsters.
The entire domain is meant to have a true Lovecraftian horror feel. I see it has having the feeling as the Mountains of Madness, where everything just feels wrong and off, and then any encounter pushes the envelope of grotesque body-horror (my first immediate thought is use tadpoles on various creatures to create facsimiles of the head-crab zombies from Half-Life).
As the dark lord, however, the brain is not truly happy. Its curse has a few facets. First, its grandest and most exciting experiments are doomed to fail. The true evolution, the next step of illithid evolution eludes it. Its greatest experiments on illithids end with unthinking monsters, uncapable of the kind of advanced mental capacity needed to be true illithids. Secondly, as its psionic powers have grown, they have begun to show downsides. Now, the elder brain is in constant psionic contact with any living, thinking being within its entire domain (this is the source of the dreams, which are actually semi-lucid thoughts and memories from the elder brain). However, as the number of such beings grow, it becomes harder for the elder brain to concentrate, its own thoughts increasingly drowned out by the thoughts of other minds.
Finally, and perhaps most vexxing for the elder brain, by incorporating non-illithid minds into itself, it has...changed. These brains did not become absorbed into it in the same manner as illithid brains would, and now at times the elder brain has vivid memories of things it never experienced, desires and wishes that are not its own, and they've begun to cloud its own identity. The brain is losing the ability to sort between its own mind and the minds it has absorbed. It occasionally loses itself in thought, reminiscing about a life it used to live in a small mountain shack with its wife and children, or dreaming of its desire to grow up and become a proud soldier defending its country against barbarians. In its times of pure lucidness, the elder brain realizes that the more minds it takes in the greater these delusions grow and the more it loses control over its true self. Even worse, it realizes that because its just a giant brain forever stuck in a brine pool, it can never truly experience these new dreams and memories in the way it finds itself craving to. However, the elder brain has chosen to interpret these downsides as the beginning stages of its ascent to true godhood, and so continues seek out new minds to be added to itself.
Footnote 1: I've already created an entirely new psionic discipline (bio-manipulative) for an ancient empire on my own world, and it works perfectly here as well.
Footnote 2: By experimenting on its own kind and, eventually, itself, the elder brain pushed its acts of evil too far for even most illithids. For a race with a strong, innate sense of superiority, to even consider mixing yourself with lesser beings is morally repugnant. To actually do so, and to do so as an elder brain, is committing an unforgivable sin, turning yourself into a lesser abomination.