Ilsensine, the Great Brain

The terrible and powerful patron of the illithids is Ilsensine, the Great Brain. A deity of pure mental energy, it exhorts its followers to take their rightful place of domination over all other races of the multiverse. There’s been a lot written about illithids over the years, so this one took a lot of research and I’m pretty sure I still missed a lot of potentially relevant material, but it was still a lot of fun to write!

Ilsensine (PDF Version)
(The Great Brain, the Tentacled Lord)
Greater Power of the Outlands, LE

Portfolio:                 Mental dominion, magic, superiority, psionics, secrets, illithids
Aliases:                     Lugribossk
Domain Name:           Outlands/the Caverns of Thought
Superior:                   None
Allies:                       Gzemnid, Maanzecorian
Foes:                           Blibdoolpoolp, Callarduran Smoothhands, Deep Duerra, Diirinka, Diinkarazan, Dugmaren Brightmantle, Ghaunadaur, Great Mother, Ilxendren, Laduguer, Laogzed, Piscaethces, Psilofyr, the drow pantheon, the orc & goblinoid pantheons, most other powers
Symbol:                     Glowing brain with two tentacles
Wor. Align.:             LN, N, CN, LE, NE, CE

If knowledge is power, then the Great Brain that is Ilsensine (ill-SEN-seen) may well be the most powerful entity throughout the planes. The Tentacled Lord represents the extreme arrogance of a supreme intellect, epitomizing the mantra that knowledge is power. This great psionic being is the patron and creator of the illithid race, directing them to conquer all other races.

Illithid mythology about their creation reflects the arrogance that epitomizes their race. While they hold that Ilsensine is as old or older than the other prime creator deities, they believe that they were created much later. In their telling, while the gods of humans and orcs and elves were fumbling around with their poorly formed early creations, the Great Brain pondered and deliberated over ever feature until it arrived at the singular, perfected race of mind flayers. Instilling in them their incredible mental powers, Ilsensine then released them onto the planes with the direction to conquer and dominate all other life, as befitting such a superior race.

Other races tell a much different story. Their mythologies point to the parasitic nature of illithid society, which cannot survive without the existence of other intelligent races, to claim that Ilsensine’s creation is simply predatory rather than superior. In their view, the Great Brain copied other creations, but bent them towards destruction and with a desire to knock down everything else that the other gods had created. Other tales describe the illithids as invaders from somewhere, or even somewhen else, while a handful of tales describe them instead as corrupted and rejected offspring of another race, banished into the deep depths of the earth, from whence they eventually returned as the frightening mind flayers after many eons.

From its caverns near the center of the Outer Planes, Ilsensine stretches its neural ganglia out to capture knowledge and secrets from across the planes and the many worlds of the Prime Material Plane. Some say there are no secrets in the multiverse that are unknown to it, and illithids hold that it is an omnipresent mental being. However, the more skeptical claim that the Great Brain simply has a lot of well-hidden spies in the form of cranium rats and intellect devourers and has consumed so many minds that it simply has such a powerful intuition that it simply appears to know a great many secrets. In either case, Ilsensine holds great knowledge and there are many willing to brave the dangers of its realm to gain the tiniest portion of that knowledge.

As would be expected of a power who directs its followers to conquer all other life, Ilsensine has few allies. Its truest ally is Maanzecorian, the only other illithid power. While the Philosoflayer is independent of Ilsensine, he is deferential to the Great Brain, always assuring the Tentacled Lord that he has no desire to usurp the prime role as the patron of mind flayers. Some sages claim there was once another illithid power named Lugribossk who dared to try and rival the Great Brain, only to be subsumed by the Tentacle Lord’s greater power; most other sages dismiss this as post-hoc speculation about one of Ilsensine’s different forms, however. Ilsensine is widely believed to have an alliance with the beholder power Gzemnid, the Gas Giant, in part due to their connected realms. Rumors claim that Gzemnid managed to withstand the ever-present psychic burn in the Great Brain’s realm and even traded knowledge Ilsensine lacked for an alliance. Darker rumors claim instead that the Tentacled Lord managed to gain mental domination over the Gas Giant during its visit, although most dismiss this idea. Finally, Ilsensine seems to have some sort of agreement with the dwarven power Dumathoin, although the specific nature of their relationship is unknown; whatever it is, however, it is known to not be a full alliance. On the other side of the coin, the Tentacled Lord could be considered to be the enemy of virtually every other power, for its followers ultimately wish to enslave or destroy all other sentient races. In practice, its current foes are generally regarded as the patrons of those races illithids are in close conflict with. However, Ilsensine reserves its greatest hatred for the twin derro powers Diirinka and Diinkarazan. The pair long ago raided a storehouse of the Great Brain’s magic, but only Diinkarazan suffered retribution at Ilsensine’s tentacles. The betrayed brother now sits imprisoned on a layer of the Abyss, his mind broken by the constant barrage of horrors Ilsensine channels into his thoughts. Diirinka has so far escaped the same fate by hiding and isolating himself in his own realm.

If there is one saving grace for the rest of creation, it is that Ilsensine is so supremely arrogant that it is frequently absorbed in brooding fantasies and plots of domination. The Great Brain feels that little can truly threaten its eventual domination of all life, so it acts infrequently and pays little attention to minor setbacks. Only if dire catastrophes face its followers may it be moved to act, as legend says it did in the Astromundi Cluster to destroy hordes of fiends bent on the sphere’s domination. Otherwise, it typically sends an avatar to observe or attend a conclave of illithids who are planning a substantial territorial expansion in plans that will take decades or longer to come to their conclusion. It also occasionally appears to absorb the minds of great sages or scholars that its followers have captured and offer up in a sacrifice. Finally, it may manifest if an illithid community has greatly displeased it in order to teach it a devastating lesson, often by eating half their number.

Ilsensine’s Avatar (Mage 40, Psionicist 40, 30-HD Mind Flayer)
Ilsensine appears as an enormous floating green spectral brain with two tentacles and glowing with an eerie light. It can also appear as a tall ulitharid with great physical power, typically called Lugribossk, although this is rare and typically reserved for locations where the Great Brain is worshipped in a more illithimorphic form. It draws its spells from all schools and uses all known forms of psionic devotions and sciences.

AC −5; MV Fl 12 (A); HP 260; THAC0 1; #AT 2
Dmg special ×2 (tentacles)
MR 80%; SZ L (8 feet long)
Str N/A (20), Dex N/A (10), Con N/A (20), Int 22, Wis 23, Cha 20
Spells W: 9/9/9/9/9/9/9/8/8
Psionic summary: Mental #AT: 2; Mental THAC0 −5; Mental AC −10; Dis all/Sci all/Dev all; PSPs: 750; Att all; Def all.
Saves PPDM 8; RSW 3; PP 5; BW 7; Sp 4

Special Att/Def: Ilsensine prefers to use psionics or magic when confronted with a threat; if necessary, it can strike with both of its ephemeral tentacles. These tentacles are 10 feet long and ignore all AC bonuses for armor and shields (except for magic and Dexterity), and a strike drains either 1d6 points of Intelligence or Wisdom, as desired by Ilsensine, and restores 1d6 hit points to the Great Brain. A victim reduced to 0 Intelligence or Wisdom becomes a mindless husk of a being wholly controlled by Ilsensine equivalent to a juju zombie. As a being of pure mental energy, it has no physical ability scores, but for the purposes psionic power scores and comparison to how much it can lift with its tentacles and how the form reacts, it has an equivalent of 20 Strength and Constitution and a 10 Dexterity.

The Tentacled Lord has a mind blast like illithids but with double the area of effect. It can cast mass charm and mass suggestion three times per day, and once per day it can project a prismatic spray.

Ilsensine is immune to spells below 4th level and weapons below +2 enchantment. No spells or psionics that directly affect physical ability scores have any effect on it, and it cannot be harmed by caused wounds, energy drains, paralysis, and petrification, and it immune to all spells and psionics that would exert mental control.

Other Manifestations
Ilsensine is not an active power in the lives of its followers. It communicates not through omens or signs, but by direct telepathy and then typically only with its most powerful and favored servants. It acts rarely to aid its followers outside of sending an avatar, although it has been known to reward especially devout illithids who have offered great sacrifices it its name with the ability to cast a handful of spells, usually 1d4 wizard (70%) or priest (30%) spells of levels 1–6 that can be cast once per day each for 1d4 days. Illithids often make large sacrifices before major attacks or other excursions in hopes of garnering this aid.

Ilsensine is served primarily by eaters of knowledge, cranium rats, and intellect devourers, but also works through brain golems, brain moles, brain spiders, cerebral parasites, grimlocks, incarnates of pride, rautym, su-monsters, thought-eaters, and ustilagor. It never displays its favor or disappointment to followers through any discoveries, instead conveying its thoughts and feelings through direct telepathy. Such communications are not common, and usually the result of great actions or terrible mistakes made in the Tentacled Lord’s name.

The Church
Clergy:                      Specialty priests, psionicists
Clergy’s Align.:      LN, LE, NE
Turn Undead:           SP: No, Psi: No
Cmnd. Undead:         SP: No, Psi: No

All specialty priests of Ilsensine receive religion (illithid) and reading/writing (qualith) as bonus nonweapon proficiencies.

The faith of Ilsensine dominates illithid society; it is beyond rare to encounter a community that does not at least pay lip service to the Tentacled Lord. However, their faith in their patron is substantially different from most other creatures, as they have few services and even priests dedicated to the Great Brain are rare and usually transient. To an individual mind flayer, rather than passing on to an afterlife, they see their end as a merging with their community’s elder brain so their knowledge and spirit aren’t lost to their people. They see their patron as the origin of their powers and the one who dictates their manifest destiny; their existence is itself an act of faith, so they see little need for frequent ceremonies. When priesthoods do form, it is usually due to an event such as an appearance of one if Ilsensine’s avatars, and the religious fervor such events cause generally fade within a generation. While existing, they attempt to guide their community towards the explicit goals and desires of the Great Brain while not attempting to usurp control from the elder brain and ruling concord (although they are always included in the concord as all recognized factions are). The only other faith accepted into illithid society at large is that of Maanzecorian, and priests of both gods work well together. Occasionally cults dedicated to other powers of domination form but the followers of Ilsensine are quick to eradicate them and such faiths only ever gain stability and acceptance in exile communities that lack an elder brain. The faithful of Ilsensine are willing to work with outside faiths and peoples with few exceptions so long as it serves a greater goal, and such alliances never last longer than the community benefits from it. There are cases where stable alliances last for hundreds of years due to the continued benefit such alliances pose, but the illithids themselves always see the alliances as ultimately transitory.

Temples dedicated to the Tentacled Lord can be found in any community that currently contains, or has contained in the recent past, a group of faithful priests dedicated to Ilsensine. Temples typically are designed as a long hall ending in a large round chamber dominated by a great stone idol of a tentacled brain. The tentacles are carved so that they appear to be burrowing into the floor around it; the long hall is lined with columns carved to appear as the terminal ends of these tentacles bursting through the floor and coiling up to and into the ceiling. This chamber is public to all illithids, while leading off this chamber are the private quarters and chambers for the priesthood and acolytes. These quarters are closed off at times when the priesthood atrophies or dies off, but the temple is always maintained. In small communities, temples are constructed that consist of a single chamber with an idol of the Great Brain placed above a simple altar. The idol is rarely much larger than a human brain in size, but may be carved of jade, green marble, or another valuable stone.

Novices in the service of the Great Brain are called Ganglions; full priests of the Tentacled Lord are called Neocorticans. Specialty priests are called cephalords. While the titles used by the clergy often varies from community to community, the most common titles used, in ascending order, are Mindlinker, Mind Wiper, Mind Dominator, Psionic Blaster, and Ultrablaster. The clergy of Ilsensine is almost entirely composed of specialty priests (95%), with the remainder consisting of psionicists (5%). Similarly, illithids (93%) make up the vast majority of the priesthood while ulitharids (6%), when found, always quickly rise into the upper ranks; the only other creatures found within the clergy are rare priestly elder brains (less than 1%).

Dogma: Dominion over all other life is the natural order for Ilsensine’s creation. Other creatures are like cattle; use them, corral them, and feed on their minds. Knowledge is power; seek it out and wrest it from those who hold it. The mind is both a tool and a weapon; hone it and use it to the greatest effect.

Day-to-Day Activities: Within illithid society, priests of Ilsensine form the Venerator creed, one of many guild-like social structures that constitute the whole body of the community under the elder brain. Within this creed, the clergy of the Tentacled Lord advocate for the issues they believe will benefit their divine patron in particular, as well as pushing to expand the creed into other communities where it is currently not found. There is always a great deal of political maneuvering between creeds; as such, the influence of the Venerators varies wildly from community to community. Besides advocating for Ilsensine’s positions in illithid politics, they also spend a great deal of their time venerating the Great Brain, both in private creed-only and public ceremonies.

Important Ceremonies/Holy Days: Holy days vary between communities and are dictated by the local Venerator creed; those with no Venerator creed rarely observe any holy days at all, reserving their worship for Ilsensine to personal and mental reverence. Holy days are often centered around the founding of the community and the formation of their elder brain, the foundation of the local Venerator creed, the conquering of powerful rivals, and great psionic epiphanies that lead to the creation of new mental disciplines that benefit all illithids. On average, the Venerators hold one ceremony per month, with two or three public and the rest reserved only for members of the Venerator creed.

Major Centers of Worship: The nature of illithid theology is such that the concept of holy pilgrimage is foreign to them; however, in some cases illithid clergy of the Tentacled Lord travel to location of major temples in order to hold conclaves with their fellow priests from other communities. As such there are some significant temples dedicated to Ilsensine on many worlds.

One of the largest temples is the Craniumeum on the world of Falx, a truly enormous temple located near the heart of the city Brain-in-the-skull. This temple is the center of that city’s Venerator creed, and home to over three hundred priests and thousands more lay followers. The head of the order is a mysterious ulitharid known simply by its title the Cephalovore of Ilsensine; nothing is known about its origins other than it has been Creedmaster for at least two centuries. Many of the lay followers believe it to be divinely touched by the Tentacled Lord, and this reverence has caused significant consternation among the city’s Elder Concord, and the elder brain, for whom the city is named, is careful of the Cephalovore’s motives, often attempting to subtly oppose them without obviously doing so.

Another great temple lies within the capital of the illithid empire of Clusterspace, located on the planet Ushathranda’s moon Illimandra. This temple, known as the Dome of Lugribossk, holds the true ruler of the empire, a greatly weakened avatar of Ilsensine in the form of a powerful illithid known as Lugribossk, the Clusterspace name for Ilsensine. It originally appeared in millennia long past to destroy a host of planar fiends that threatened the sphere. The illithids, through the ruling Venerator creed, are actively trying to release the imprisoned avatar’s greater powers, although only time will tell if they are successful. Possibly unique among major illithid communities, the illithids of Clusterspace are quite open to the use of wizardly magic and have given rise to a unique creed known as the Thaumaturge creed; these sorcerous mind flayers are junior to the Venerator creed of the empire but aim for a greater position through complex political maneuvering. As yet the avatar Lugribossk has said nothing about this caste in its hour-long waking periods each day.

On the world of Oerth, one of the most prominent illithid cities is Dra-Mur-Shou, located near the Sunless Sea deep beneath the surface. This city is home to a stable but politically weak Venerator creed, centered in the temple complex known as the Gyral Halls of Ilsensine in the High City. This creed advocates for the joining together of all illithid communities throughout the underdark beneath the Flanaess into a single confederation in order to further the Great Brain’s goals of domination. As yet, they’ve found little support for this among the rest of the city’s creeds but are encouraging the Venerator creeds in other settlements to advocate the same goals.

In Realmspace, orbiting the illithid-dominated world of Glyth is a hollow moon called Haven. This small moon is neutral ground for the rival illithid factions to conduct trade and negotiations, but it also contains a mind flayer faction of its own. Only one creed exists within this community, a unique fusion of the Venerators and the Possessors who believe it is their religious duty to facilitate trade among all illithids while also gaining wealth through the fees they charge for running the open port. The whole moon is in essence a temple dedicated to Ilsensine; all illithids in good standing with the Tentacled Lord and with non-violent intentions are welcomed within.

Faerûn is arguably home to an even more important site to Ilsensine’s faith in Realmspace. The city of Oryndoll, beneath the lands west of the Vilhon Reach, is the site of two manifestations of the Tentacled Lord’s avatar many centuries apart. After the first appearance, sent to restore order in the wake of a disastrous thrall uprising, a great temple known as the Grotto of Sacred Thoughts was constructed by the newly established, and permanent, Venerator creed. During the Time of Troubles, Ilsensine was forced to appear a second time, reinforcing the holy nature of the city. While illithids from far-flung cities do not engage in pilgrimage to this city, they do still hold it in reverence and hold great respect for the priest cast of the city.

Affiliated Orders: Both because of the nature of illithid society and the system of creeds, all clergy of Ilsensine are members of the Venerator creed. Within any given settlement, the Venerator creed may have traits associated with monastic orders, military orders, or even merchant guilds, depending on what other creeds are found within the settlement. As such, no independent orders are ever sponsored by the priesthood of Ilsensine.

Priestly Vestments: Priests of the Great Brain wear fine hooded robes of high-quality cloth with a high-collared cloak. Both the robe and the cloak are of the same color, and fringed with non-geometric tentacle-like patterns which are sometimes mistaken for flames. In some communities, the colors of the robe and fringe vary based on the rank of the priest, but every group of priests embroider symbology to denote rank on the cuffs of the robe. Some clergies wear ceremonial daggers or other blades at their belts, and decorative belt buckles are quite common. The holy symbol used by the priesthood is an amulet emblazoned with a brain in the center and a pair of tentacles that wrap around the edges. These amulets are psionically enhanced and “glow” to the telepathic sense of illithids and other psionic creatures.

Adventuring Garb: The Tentacled Lord’s clergy rarely leave their enclaves except in times of great conflict or to negotiate with other settlements, mind flayer or not. Little obviously separates them to the eyes of non-mind flayers, but other illithids can always sense when they are in the presence of a priest of Ilsensine. They do not seek to hide their status to other races, but neither do they advertise it. As with other mind flayers, they let their thralls do most of the fighting, relying on their psionic and magical might when in danger. They are more eager than their brethren to gain magic items, however, and the more powerful among the clergy often seek out additional protections and staves, rods, and wands they can utilize. They almost never wield weapons, however.

Specialty Priests (Cephalords)
Requirements:          Intelligence 14, Wisdom 14
Prime Req.:                Intelligence, Wisdom
Alignment:                LE
Weapons:                   Any
Armor:                       None
Major Spheres:         All, astral, charm, divination, law, sun (reversed), thought, time, wards
Minor Spheres:         Guardian
Magical Items:         Same as clerics
Req. Profs:                History, ancient
Bonus Profs:             History, local

  • Cephalords must be illithids, ulitharids, or elder brains.
  • Cephalords are not allowed to multiclass.
  • Cephalords may select nonweapon proficiencies from the psionicist group without penalty, if those rules are used.
  • Cephalords cast all spells from the Thought sphere as if they were two levels higher.
  • Cephalords can cast wizard spells from the school of mentalism as described in the Limited Wizard Spellcasting section of “Appendix 1: Demihuman Priests” in Demihuman Deities.
  • In order to aid in the casting of their priestly magic, all cephalords have reduced magic resistance. Rather than the standard 90%, they have a magic resistance of 18%.
  • Cephalords can cast charm person (as the 1st-level wizard spell) once per day.
  • At 3rd level, cephalords can cast idea (as the 2nd-level priest spell) once per day.
  • At 5th level, cephalords can cast suggestion (as the 3rd-level wizard spell) once per day.
  • At 7th level, cephalords can cast phantasmal killer (as the 4th-level wizard spell) once per day.
  • At 10th level, cephalords can commune (as the 5th-level priest spell) with Ilsensine once per week. This use is in addition to any normal limits placed on the frequency of casting the spell.
  • At 15th level, cephalords can cast divine inspiration (as the 7th-level priest spell) once per week.

Ilsensite Spells
2nd Level
Enhance Blast (Pr 2; Alteration)
Sphere:                    Thought
Range:                     Touch
Components:           V, S, M
Duration:                 1 rd./3 levels
Casting Time:          5
Area of Effect:         1 creature
Saving Throw:        None

With this spell, the mental attack powers of a single touched creature are amplified and heightened for the duration of the spell. While primarily used to enhance the innate mental blast of illithids, it also benefits telepathic psionic attacks and spells from the school of mentalism and the sphere of thought. All saving throws against these abilities and spells are made with a −1 penalty for every five levels of the caster, and any duration effects are extended for the same amount in rounds. Further, if the attack causes damage, it gains a +1 bonus to each die, even if the damage is illusory. When this spell expires, it leaves the affected creature mentally exhausted and unable to use any spells, psionics, or other innate abilities other than telepathic communication for one turn.

The material component for this spell is the priest’s holy symbol.

3rd Level
Pierce Mental Barrier (Pr 3; Alteration)
Sphere:                    Thought
Range:                     30 yds.
Components:           V, S, M
Duration:                 Special
Casting Time:          6
Area of Effect:         1 creature
Saving Throw:        Neg.

By means of this spell, the caster is able to pierce a magical or psionic mental barrier in effect on a single target. The target is allowed a saving throw versus spell to avoid the piercing, with a penalty equal to the caster’s Wisdom magical defensive bonus. For example, a caster with a Wisdom score of 15 would inflict a −1 penalty upon a target. The saving throw does not benefit from a high Wisdom, but a low Wisdom score does inflict an additional penalty.

This spell instantly dispels magical protections like mind blank and impregnable mind. In the case of spells like protection from evil that offer a partial protection from mental attacks or control, then the pierce mental barrier spell eliminates only that portion of the protection, leaving the rest in place. Finally, in the case of psionic defense modes and other protections, this spell prevents the use of the current defense mode a target has in place for a number of rounds equal to the caster’s Wisdom defensive adjustment, plus 1d4 rounds.

Affected creatures always feel a successful casting of this spell in the form of a sharp mental stabbing sensation that carries no debilitating effects.

The material components for this spell are a gold needle and a small piece of brain tissue from an intelligent creature. The needle must be pierced through the brain tissue at the time of casting, and both are expended in the casting of this spell.

5th Level
Ilsensine’s Lash (Pr 5; Invocation/Evocation)
Sphere:                    Thought
Range:                     0
Components:           V, S
Duration:                 1 rd./level
Casting Time:          8
Area of Effect:         10-foot lash
Saving Throw:        Special

This spell creates a ten-foot-long glowing green tentacle-like whip of force in the caster’s hand. They may attack as if proficient and any targets are treated as having Armor Class 10, modified only for Dexterity and magical protections. Creatures struck lose one point of Intelligence or Wisdom (50% chance of either) and must make a saving throw versus spell; if the save is failed, they instead lose one point from each score. At the same time, the lash transfers the energy lost to the wielder, healing them for 1d6 hit points per lost ability point (i.e., 2d6 in the case of a target failing their save). Any creature reduced to zero Intelligence or Wisdom dies immediately.

Lost ability points return at a rate of 1 point per hour, typically alternating until all points are restored. The wielder of the whip can make use of no psionics or mental abilities while the lash is in effect, but they can choose to not attack in any given round to cast a spell or make another physical attack.

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