Ilsensine

Ilsensine was the patron deity of the illithids, though not their creator. It was also the patron of evil mages and psionicists who dominated the minds of others. Its true appearance was as a disembodied brain of emerald color that trailed countless ganglion-like tentacles.

Personality
Ilsensine was cold and calculating, using magic and its psionic strength in a merciless combination to manipulate events as it saw fit. It used its psionics to gather information as well, pulling it from the minds of all mortals within the Prime Material Plane and beyond.

History
Ilsensine made itself known in the Realms immediately following the duergar uprising against the illithids in approximately -4000 DR. The city of Oryndoll nearly collapsed from the resulting chaos, and only the sudden appearance of an avatar of Ilsensine saved the city from tearing itself apart. Since then, the mind flayers of Oryndoll developed a highly religious culture, along with many innovations in the field of psionics.

Worshipers
Besides illithids, any who sought to dominate and enslave the minds of others may have felt drawn towards Ilsensine. It offered power and control to those faithful to it, along with access to the Mind domain of divine magic. Its clerics were known as accomplished slavemasters, using both magic and psionics to control living and undead slaves alike.