Proxy
Common40.0%ObjectiveOptional
Kill a squad that just finished off another squad and won the fight. Or so they thought…
This can be achieved without much effort through normal play - you'll come across various squads in the world; let them battle each other and then kill the winning team. See the video though for one particular place in the Warlock Debtors side mission where this can be reliably gotten.
How to get the Proxy achievement