Mynisera will ask you to retrieve the emperor's letter from Gortwog, King of the Orcs and promise him her assistance in getting the emperor to declare the Orcs a sovereign and seperate power.

Gortwog will then allow you to search his fortress for the letter. The easiest way to find the letter is to enter the door on the left behind Gortwog and follow the right wall until you reach an open area where you will see a fountain with a skull in it. Jump in the fountain and you'll be transported to the balcony overlooking the room. Go up the stairs to your left and keep following the right wall, through two caves and finally into a huge amphitheater. In the center of the room you will see a table and on it is the emperor's letter. Take the letter back to Mynisera and she will tell you about the Totem of Tiber Septim.

Shortly after you leave Castle Daggerfall you may receive an anonymous message explaining that the Totem is a key that controls a giant called "Numidium" but the giant's Mantellan heart must be found before the giant can be reactivated.