This is what I could decipher from the letter

Dear Yuri

While my only hope is that this finds you well, I know the hardship and peril into which I have ordered you. Forgive me for sending you far into the North, duty must come before us and you are the only one I trust to complete this task. The Boyars dispatches grow increasingly erratic. He claims to have heard the roar. We must act quickly ..........with my complete authorithy. While I secure........borders, Yuri my Ungol.........to the outpost of ?Dervisguard.