You cannot complete the mission if you already talked to the person about killing all the Blueskins. This mission actually starts beforehand. After killing Rust in the single security level, there is a Blueskin in the courtyard on your way back there. Talk to him and he will congratulate you on killing Rust. Kill him when a guard is not nearby. This Blueskin cannot be found afterwards. Note: The Blueskin in the Single Max section is not on the Blueskin kill list because he dies in the cell block riot. The final Blueskin needed to complete the mission is in the upper mines. He gives you information about a keycard carrying guard you need to kill. Kill him immediately, or afterwards.
There are two parts to the snitch list. One part is hidden in the work pass room where there are the two guards and the mechanic. Search for a loose panel behind the crates. After giving the package to Jagger Valance and getting the mission to get the bomb, return to the second floor as if you are going to the upper mines. On your way back you will encounter two miners standing around. Kill them. One of them has the second part of the snitch list.
Abbot uses a attack pattern that consists of a left to right swing followed by an overhead smash. After he completes that pattern, attack him two or three times with the shiv. Repeat this to kill him.
Turn on all the valves you find. If any type of guard stands near a valve that is on, they will pass out.
To defeat riot guards, shoot a shotgun a few times at the black panel on their backs.
Use the minigun to destroy the robot guards in the final battle. Try to line the robots up for better results. The force of the gun will push the robots. If they are in line with each another, they will both become helpless.
Fight Bam in Double Max. If timed correctly, you can get his Knuckleduster as soon as he dies. Note: It will not be here if you return after you kill Abbott.
When you are low on health, eat one of the flying bugs to restore your health.