This is my interpretation of Illithinoch from Lost Mine of Phandelver & Below | Shattered Obelisk.

The mind flayer lair has changed from its original intention, due to the delusions of a paranoid elder brain, though it is no less deadly or dangerous. I’ve added in several additional details, including the Elder Brain itself, along with some choices in the various rooms to reinforce the mood.

I’ve included an illustration of an Illithid by Alicia Martinez that was created for the Morvold Fantasy Art Gallery, to provide some sense of mood, as well as a token. I’ve also included a token of an Elder Brain, by Dean Spencer.

The Elder Brain chamber has some runes upon the floor that I choose to represent by linking multiple runes into what appear almost as heiroglyphs or scripts, forming a combination of meanings by both the individual runes used as well as the shape and meaning of the whole.

While the dungeon is dressed for the descriptions of the module, it could certainly function in your own homebrew world as an Underdark location for the party to explore.

I’ve included a version of the location with and without the Elder Brain on the map, as well as a token of the Elder Brain that can be placed in that location.

I hope you enjoy it!