Halo Wars 2

This achievement is purely luck-based but it won't be too difficult to obtain regardless of how late you jump into the online portion of the game. Essentially, this is a viral achievement that is earned for killing someone who already has the achievement (which they likely earned for killing a developer's unit around the launch week of the game).

Don't put too much thought into this achievement; just play match-made Multiplayer games and this will come sooner than you can expect.