Borderlands 2 Walkthrough Part 19 – Sanctuary Sidequests, Part 4: Assassinate the Assassins
 
Assassinate the Assassins (Southpaw Steam & Power)
Head to the Bounty Board to the East of the Fountain in the center of Sanctuary. Here you can find the Side Quest, “Assassinate the Assassins.” You will need to return to Three Horns to start this mission, but take your time to collect all the side quests found in this area. After that head over to Three Horn – Divide to find the starting point of this quest. At the first marker you will need to fight your way through a number of Nomads and Crazed Marauders who are guarding the entrance to the Southpaw Steam & Power. Once inside you just need to head forward.

Optional Objective:
Kill Wot with Pistol
Head on forward into the Steam & Power. Start by going to the East and clearing out who you can. Continue up the stairs to the East and around the corner to find a shutter door. Approach it to trigger Wot's appearance. If you want to complete the optional objective, be sure to kill him with a pistol. After that you will be presented with the second target.

Optional Objective:
Assassinate Oney with Sniper Rifle
Head over to the East after you kill Wot and up the stairs. Time for you to face down a large collection of Crazed Marauders, Psychos and a few Nomads. Kill your way through them. Take your time to work through the crowd as best you can. There are a lot of tough enemies inside it especially in the later part of it. More Nomads and some Suicide Psychos will appear after you have taken out the first wave. It is also in this wave that you will encounter Oney. Blast through his support then focus on him. Once again, be sure that you kill him with a Sniper Rifle to complete the optional objective. The problem here is just how many people are around him. He is accompanied by a number of Suicide Psychos, some Nomads and a few Crazed Marauders. It takes some real effort to cut through them and get to him.

Optional Objective:
Assassinate Reeth with Melee
Head to the Northeast from where you fought Oney and you will be on track to find Reeth. Head down the stairs of that doorway then start over to the West. At the bottom of the stairs you start with a few Crazed Marauders. Continue to the West after that to find the doorway that leads to where Reeth is to the South. Cross the threshold and head down the stairs to the right. You will find Suicide Psychos, Nomads and Crazed Marauders to deal with. You need to fight your way through them all. Once you make it through them all and to the Southern part of the room you will find 2 shutter doors. The first unleashes a wave of Crazed Marauders with a few Suicide Psychos thrown in. Defeat them and the second shutter will open revealing Reeth along with a Badass Nomad. Reeth is the Psycho for a change so he will be charging at you and lighting you on fire with his flaming axes. Defeat them both to move on.

Optional Objective:
Kill Rouf with Shotgun
Head to the Shutters and proceed to the Southwest. This time you want to head up the stairs. When you get to the top, past the lockers and chests, you will find yourself facing Crazed Marauders and at least one Nomad. Defeat them and a wave of Burning and Suicide Psychos will come straight at you. Defeat them to face a wave of simply Burning Psychos. This is followed by Assassin Rouf showing up with 2 Nomad Taskmasters. Focus on Rouf as he will be bouncing around and firing at you, then worry about the Taskmasters. To finish out the head just head to the North from the Shutter that Rouf came through. From there just head on toward the door and leave Power & Steam.