Ilsensine is the patron deity of illithids (also known as mind flayers). While not the creator of illithids, Ilsensine sees mind flayers as the entities most worthy of dominating the universe. Ilsensine is obsessed with gathering knowledge of all varieties, and its ganglia stretch to every corner of existence, tapping into all the knowledge of the universe. The Symbol of Ilsensine is a brain with two tentacles protruding from it.
Ilsensine cursed the derro god Diinkarazan and seeks vengeance against Diirinka, who successfully stole from it. It was formerly served by the illithid god Maanzecorian, who was later killed by Orcus. Ilsensine is an enemy of Lolth and Laduguer, but is allied with Kiaransalee.
Ilsensine dwells in a series of caverns beneath the Dwarven Mountain in the Outlands called the Caverns of Thought, along with a vast army of mind-controlled thralls. This realm is intertwined with that of Gzemnid, and stretches near the gate-town of Glorium.