Middle Earth: Sunset of the Fourth Age
Supreme Leader of the Far East
In other words, Sauron.
While the party has not yet met the SLFA in person, he revealed himself to be Sauron (or perhaps Sauron’s shadow possesses the SLFA) through a captured enemy soldier in A Surprise Visit.
400 years ago their Supreme Leader went from being one of their greatest mages to someone indescribably powerful and much more ruthless and cruel. They don’t know what changed him, but they do know that their leader may be strong enough for them to conquer the West and take their rightful lands back from those that have denied them their birthright.