For this Challenge, you need to kill Skags. While they aren't as plentiful as they were in the first game, there are a few spots where you are able to farm the kills, such as Arid Nexus - Badlands and Arid Nexus - Boneyard.
- Rank 1: Kill 10 Skags
- Rank 2: Kill 25 Skags
- Rank 3: Kill 75 Skags
- Rank 4: Kill 150 Skags
- Rank 5: Kill 300 Skags