Easy Achievement! Can be done on Versus Private within 5 minutes. And also you can do it on SOLO vs AI or Duel Controller to hunt more quickly...
VERSUS --> CUSTOM --> LAN GAME --> HOST GAME
Map : Any
Game Setup : ARCADE DEATHMATCH (set as BEGINNER in DIFFICULTY)
to Start Match.
Now run into enemies and die fast as you can.. just remember who killed you.. and then on respawn screen press
to change character (Example : Kait to markus)
Now search for that enemy who killed you and take him out..
wait for sometime to pop... and sure it'll pop if you've done correctly...
UPDATE : Thanks to Ivan610
During Game setup, You can lock your other 4 team members and in opponent team lock 4 members & leave 1 slot open for bot. then it should be 1v1. so easy to kill.
I've also uploaded a video for it... take a look...
Comment why.. if you voted negatively.. so that i can correct my solution.