This quest is actually very easy. First you talk to Nazir who tells you to go to Whiterun to confirm with Amaund Motierre that the assassination is still a deal. Afterwards you go to the Katariah which is laying under Solitude in the ocean.
On Board the Katariah
On Board the Katariah you encounter many of Penitus Oculatus Agents. Your best bet is to use stealth and a bow and arrow as you can catch many guards by suprise or even kill them before they discover you. I found that this made this quest very easy and I didn’t even come close to dying once. Eventually you find yourself on the deck of the Katariah. There are about 4 Pernitus Oculats Agents on deck. Kill them with stealth. Next you go to the Emperors quarters where you find Emperor Titus Mede II sitting behind his desk defenseless.
After you have done the deed report back to Nazir in the Dawnstar Sanctuary.
This quest is fairly easy, it consists of a lot of story telling. First you have to kill a number of Penitus Oculatus Agents. They are fairly easy to kill as they are weaker than guards. I even used a bow and arrow in close combat and was easily able to dispatch them.
Inside you find Nazir fighting Arcturus. I found that satying out of the fight and using a bow and arrow to get shots on Arcturus was the easiest way to kill him. Don’t worry about hitting Nazir, he can’t be killed and he won’t turn on you if you shoot him too much.
To escape the fire you get into the coffin of the Night Mother. I am not sure how Nazir and the girl survive, but they do and they pull you out of the water. Afterwards you talk to Astrid and she eventually asks you to kill her with the Blade of Woe.
This quest is actually very simple. You have already got the required paperwork to get inside the palace. In the making of the Potage Le Magnifique you can add anything you want to the dish, Gianna won’t question it since you are the Gourmet. At the end be sure to add the Jarrin Root, it will save you from manually killing the Emperor.
Killing the Impostor of the Emperor of Tamriel
If you have added the secret ingredient (Jarrin Root) the the impostor of the emperor of tamriel will die automatomatically. To speed things up you can use other means of killing him. The only thing that is important is that he dies.
Escaping the Palace Without a Bounty
After you leave the death scene you will run into 4 imperials who will try to put you into prison. They are easy to kill, although I advise against using a bow and arrow because a sword can deal out much more damage per time than a bow unless you are sneaking. You won’t have a bounty after you have killed all four guards. All of the enemies are called “Penitus Oculatos Agent” and they are much weaker than normal guards are.
After you have escaped you have to head back to the Dark Brotherhood Sanctuary that has been raided. At this point the next quest starts.
This quest is managed by Festus Krex. After you have completed “The Cure for Madness” (click for guide) Astrid will as you to report to Festus Krex who will give you he details about “Recipe for Disaster”. He will ask you to question Anton Virane who you can find in Markath in the Understone Keep.
After you have question Anton Virane you have to kill him. This is somewhat difficult to do without getting a bounty. I decided to kill everyone in the room who saw me kill Anton Virane which removed the bounty because the last witness was killed. The guards outside will probably appear as red enemies, but stay hidden and they won’t find you and eventually stop looking.
Killing Balagog gro-Nolob and Hiding His Body
To get a bonus you have to hide Balagog gro-Nolob’s body after you have killed him. It is easy to kill him without getting a bounty because he is in the basment and nobody else is around. If somebody does happen to be down there with you kill them as well and you won’t keep your bounty.
Dragging Balagog gro-Nolob’s body in a corner will do the trick. I found that the best corner was:
After you have done the deed of killing Balagog gro-Nolob report back to Festus Krex at the Dark Brotherhood Sanctuary to complete the quest and receive the next quest.