It used to be that the Eldar, even in 40k, where always led by Farseers. But in Epic: A this is only true for Ulthwé, all others have only Autarchs as options for Supreme Commanders, even in lists where the Aspect Warriors are support formations (Troupes).

Not all Eldar armies need be led by a Seer Council, but how about adding an option of giving one Farseer in non-BT armies SC at a cost of 50 pts (this option being exclusive with an Autarch of course).