Using the starting character Kinessa seems a reasonably surefire method of getting this done.NOTE #2: CRUM LEE has noted that this can apparently be done in the training mode now, making it far easier
is the starting sniper character. Try to hang back, not be noticed, and use
to zoom in and
to fire. It often helps if you lurk around corners or stick between two boxes or other pieces of cover. Be very aware of counter-snipers.
You need to hit each member of the enemy team (usually 5 unique players) at least once before any of them damage you at all. If you're careful and sneaky enough this can be done very easily.VGM 007
has an addition to this method, details in the comments, but revolves around:
"Throw your mines right near where the Payload is spawning and when the other team runs out to start pushing the payload, they'll all take damage from the mines."
This may take you a few tries, but can certainly be done with this method pretty quickly. I got it essentially by accident while trying to get the "Sniper" achievement (which you have to be quite
far away for).
If it helps, I was playing on the map that has the huge dock over the water, I'll update when I find the name of the map or if someone comments to help :) Can be done on any map though. Must be done against other players.NOTE
that you must play against bots until your account level is 5 upon starting the game before playing against other players to unlock achievements. This usually takes 4-6 games depending on if you win and how well you play.