Elder brain

An elder brain is the final stage of the mind flayer life cycle. The elder brain lives in a brine filled pool in the centre of a mind flayer city, where it guides its community by filling them with dark dreams of illithid domination. Although its intellect is of godlike proportions, its only physical attack is by using its tendrils to lash out or grapple an opponent. Therefore mind flayers protect their elder brain by securing it in a well protected cave inside the city.

Its strong mind-affecting powers stem from the brains of longdead mind flayers making up the viscious mass of the elder brain. Being composed of many brains as energy source for its intellect it can communicate telepathically with any creature within 350 ft (107.73 m) distance.

Combat
An elder brain can use its spell-quicked abilities in the same round as its tendril attacks. Usually it starts its attacks with a powerful mind blast

In combat it can use many psionic attacks such as charm and domination abilities. On top of those, it can cast spells as a 20th level sorcerer, making it an opponent to be feared.

Society
Forming the physical and spiritual centre of a mind flayer community, it serves as a living library of the community's history, technology and knowledge. Playing this important role in a mind flayer society, it often doubles as an advisor in all sorts of political and military decisions, operating as a de-facto leader.

An elder brain marks also the ultimate goal in every mind flayer's life when it nears the end of its lifespan. Mind flayers sacrifice their brain and individual life by merging with the elder brain, strengthening its powers and intellect. The average mind flayer is kept in the dark by the elder brains that their personality and consciousness is lost when joining with the elder brain and only their knowledge and ideas survive, this secret is guarded by the elder brains fiercely.