Septimus was the first defense of Thyrion against the onslaught of Eidolon and his forces. It was also the last. War now resides in the temples that were once filled with peaceful meditation and prayer to gods long forgotten. You must search these darkened temples and find the last of Eidolon's Generals and beat him at his own game.

It is only then that you will be strong enough to return to Blackmarsh, fight through the bowels of the castle and destroy the Master of the Four Horsemen. But Eidolon will not be an easy mark, for he will be waiting for you with his entire twisted arsenal.