If you don't know who Omeluum is yet, I'm not going to spoil it. It seems fairly obvious to me, that those three brain jars we can find in the epilogue on the nautiloid, should be something we can give to him, either in exchange for the thing he offers... or as an additional reward option. Same with the three illithid "books" you can find near the dead imps right after exiting the room where you pod is.
He should be absolutely giddy with excitement about those "books", after all...yet you can't even offer them to him. I want to see what something like him does he when he is happy.