Maanzecorian

Maanzecorian is the evil patron god of Mind Flayers. It wasn't always a true god, at first representing the complete comprehension of knowledge such that thoughts, aptitudes, and memories, instead of being called up as needed, are all understood simultaneously. At around the year 12 OD, this god was embodied by a group of Mind Flayers who had learned to utilize the god-creating magic of Kuo-Toa by a group of powerful hags. Since then, Maanzecorian's goals have been kept mostly secret, with his only main contribution to history being the invasion that led to the Arrival.
Maanzecorian is mainly worshiped by Mind Flayers who have begun to understand that their ideas of complete comprehension of knowledge have been given form in a god. Otherwise, it is worshiped by those who wish to gain the power of this comprehension. Otherwise Maanzecorian is the patron god of Mind Flayers, and all Mind Flayer-related monsters.
Maanzecorian is recognized as a Traveled God.
Alignment: Lawful Evil
Province: Complete comprehension of knowledge, Mind Flayers
Suggested Domains: Knowledge, Order, Trickery
Common Symbol: 10 rings all connected to every other
Appearance: A giant mind flayer made out of some sort of amorphous substance.
Residence: Maanzecorian is corrupting the Forgotten Realms with Far Realm influence, but it is a natural creature of the Far Realm.
Commandments:

• Pursue the understanding of all knowledge simultaneously, as Maanzecorian has.
• Help allow Maanzecorian and his followers to gain a greater understanding of all things of the universe.
• Spread Maanzecorian's imprint across all realms.

Other Resources

See Volo's Guide to Monsters page 80 and this article.