You'll start out the mission having to climb the water lock, so go into the water and onto the land opposite from the entrance. Start climbing up until you get into a narrow corridor, passing through the moving gears, making sure not to get crushed by them. As you turn the corner, you'll notice some openings on the left, so use the second one and go onto the ledge there.
Get onto the next ledge in front of you, then Blink to the balcony. From this balcony, with the door behind you, look up and to the left to spot an opening that you can Blink to. Follow the pipes to the next area, but beware of a patrolling Tall Boy here. Get onto the metal covering and when the Tallboy stops, Blink above him and do a drop assassination on him.
Go down the path the Tallboy was patrolling and up the stairs on the opposite end. Halfway up the stairs, turn around and Blink onto the beams above. Jump over the tall wall and go down the right area, which is void of any guard, but there is a swarm of rats. There's an opening on the left side, with a bunch of walkways, so start going on those and killing the guards you find there.
From this walkway, you can Blink onto the ledge surrounding the building, following it to a vent that allows you inside. Once you're inside and are overlooking the main room, Blink down behind the lone guard and kill him. Prep your Crossbow, shoot the guy in the red, then immediately kill the right one. Pull the switch next to the monitor and feel free to make a choice. Note that if you do the above, Lord Regent will retreat to his safe room at the top of the tower.
(OPTIONAL) KILL THE TORTURER
There is an optional objective to kill the Torturer, who is in the basement. To get there, you need to find a door on the right side of the foyer, but it isn't the one that leads outside. This door leads into the kitchen, where there is a guard and a maid, so kill them if you want. You want to take the stairs going up, then the long hallway all the way to the doorway on the slanted wall.
This will lead you downstairs to the Torturer's Room, where you'll find him beating up on a corpse, and a Wolfhound laying down nearby. Peek around the corner and shoot the Wolfhound with the Crossbow, then hide back upstairs real quick. The Torturer will investigate and come near the doorway, then start walking away, which is your chance to assassinate him from behind; he is a very tough enemy head on, so it is not recommended.
TO THE ROOFTOPS
Since the Broadcast Room is a part of the nonlethal means of finishing the mission, it's time to go to the rooftops. To get there, find the green-clothed hallway and then go to the hallways like it on the opposite side of the tower. It is there that you will find a door with stairs leading to the rooftop.
There are 3-4 guards in the first area of the rooftop, so kill them. To get inside the safe room, go on the right side and Blink to the opening there. Note that there is a Tallboy walking around inside, as well as several guards. There's not much room to work with, so your top priority it to take out the Tallboy first.
As the Tallboy is walking away towards the back of the room, Blink onto the bookshelves behind it and then above it to do a drop assassination. Alternatively, if you have Grenades at your disposal, cook them and toss them at the Tallboy's pilot. If done right, 2-3 Grenades will take him out.
Once the Tallboy is finished, head into the room and take out the rest of the guards. When all of the guards are killed, you will need to go after the Lord Regent, but he is behind a Wall of Light. To disable it, go into the room underneath and there will be a door to your left, which has stairs leading to a isolated room with the whale oil tank powering the Wall of Light.
THE KILL AND THE ESCAPE
After disabling it, go back out and up the stairs to kill the Lord Regent. After killing him, it is time to escape Dunwall Tower. Go outside and you can drop into the moat below. From here, go onto land on the left side by the walkways. You can either use the same method of escaping as with the Low Chaos walkthrough, or rush through and jump into the water in the water lock.
