I would really like it if the ring worked, plus the whole thing where you suddenly need a mindflayer feels a bit weak.
But in terms of Omeluum, in theory you are in the middle of a time sensitive battle. Someone walking to the Society of Brilliance while the city if being destroyed just to fetch him wouldn't make sense. If he were one of your "allies" for the last battle, it could work?
That is, what I mean. Or him saying, that he can feel the elder brain and wants to help us, thus having him in the camp. He just has to be near your location,when you enter the astral prison for the last time, so that he can join and offer himself as the local helpful mindflayer.
