Mindflayers procreate by cool means. They spawn little tadpoles (kikkervisjes dus in het nederlands), they nurish these and later they implant them in a host body, prererably human or drow or something. Then the tadpole takes over the hosts body and mind and slowly transforms the body into that of a mindflayer.
This rarely happens though since it's thought to be the greatest of honors... from cattle to illithid, the ultimate priviledge and ascension.
Illithid society is based on this principle:
2 thousand illithid in a large city with about 40,000 slaves and 20,000 thralls. These are the bulk of the city population.
then there are about three councils which exist of about 10-20 Illithid, one consists of the devellopers and the loremasters that keep track of literature and magic and psionics, one that gouverns daily life and organises the city and trade, and one that organises the army and defense and offense (this includes raids for new slaves and thralls on other places so they keep the slave and thrall population at a steady level.)
These three councils are ruled by a council of about 5-8 old and wise Illithid who effectively rule the city and make plans for it. They rule the three other councils and they report to them and to them alone.
Above all of this is the Elder Brain, the Elder Brain is as it says a HUGE brain which is made up of the essense of dead mindflayers. Once a mindflayer dies it's brain mass it added to the Elder Brain who then gains it's knowledge and powers. Needless to say Elder brain are VERY powerfull and their power almost of the scale. Just 1 Elder Brain exists per city, they are it's king, it's library, it's oracle, it's gateway to Ilsensine the god of the Illithid.
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This is about how it works, Illithid are divided in casts, a Illithid joins a cast, the researchers and keepers, or the merchants and diplomatics or the war and army cast. Illithid without cast are not exepted and are treated as outcasts. These exept their fate and carry no grudge against their kin in the cities, they weren't good enough or evil enough or orderly enough, they failed their kin and they exept their fate (99% of the time). They wander the planes and the underdark to do evil and do something great to regain their status in a city and to be allowed back into a cast and to fit in with their race again. Every Illithid believes that to be Illithid is to be the highest form of life and all non illithid are mere cattle and should be kept in farms for food and to do their work for them so they can live in luxury and relaxation.
So to regain a status and a place in a cast in a Illithid city is to be accepted back into perfect soceity and to be accepted back amongst the most superior species ever. So 99,999999% of the exiled Illithid try to prove themselves to be accepted back.
Hop that was a bit of help on the mindflayer subject. (Yes they are my favorite species along with Formians and Slaadi
My top 3: 1)Formians 2)Mindflayers 3)Slaadi
[Edit: The tadpoles are kept in the pool in which the Elder Brain lives, a huge pool of cerebral fluid in which the tadpoles swim and live, they are nurished by the fluid and the Elder Brain. Elder Brains are at least huge or Gargantuan Size and something like CR 30 orso... (not counting the 2000 illithid and 60000 thrall army that would guard it with their lives). They carry the wisdom power and experience of about a few hundreds of even a few thousand Illithid with them so they are with no doubt up there with the most intelligent and most wise creatures that exist on any plane, they are up there with the archdevils and demon princes. So going about killing those tadpoles would even be out of Elminsters league, even if he and his whole Mystra cast would assault a minflayer city they would die so damned fast...
Btw Elder Brain can communicate telepathically with any creature within 500 miles... So they will most likely know you are comming if their intellect and incredible and unimaginable hypercognition and precognition powers told them anyway. Out of almost everyones league
/Edit]
