This is a pretty straight forward achievement without a lot of frills or description needed. In chapter 4, about half way through the chapter, you will be told that some of the gravity panels are malfunctioning. These panels are on the floor and are a bluish color with an obvious distortion above them. These are key to the achievement.
What you want to do is to force an enemy to touch the distortion above the panel, it will instantly kill the enemy, and should count as one of your kills. You can do this by either meleeing the enemy into the panel, using stasis and then walking into the enemy until he is "pushed" into the distortion, or by manipulating an enemy's movements based on where you move, and having them walk into the damaged panel on their own.
Below is a video that I made of when it unlocked for me. As you can see from the final kill, sometimes you don't even have to touch the enemy for the kill to count.
Hope this helps, and good luck!
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