visit yormgen through phaerohs timewarp at his crag during the course of the game(after yormgen is revereted) talk to the sage there. Go beat the final boss and save your clear data. load clear data like youd load any other data, leave the final dungeon, go back to yormgen again through the timewarp and once again talk to the sage. This time youll get a book from him.
Finaly, go to dhangrest and watch a scene there, leave and fly west till you get another scene in the air, then just land and enter.