I got this on Mission 4. There are two enemies on this level with 30 health points and your target is the skinnier of the two. He walks in a random pattern, so I will tell you how to do this with ease. Grab the first spike and place it where there is the linked row of spikes. Then, go back to where you entered and go around the corner where there is another spring trap. Place it in between the row of spikes facing left. Go further left towards the spring trap right by the enemy with 10 health points and place that in between the two spikes right above where you picked it up. There should be one more trap and it is by the skinny enemy mentioned above. Grab that and wait for more traps to spawn.
When they spawn, plant another trap directly above the 10 health point enemy. Plant another trap all the way at the top of the map right above the one in between the two spike traps. After planting it, grab another trap that is close and go all the way to the left of the map and stand to the left of the trap in between the two spikes. When the enemy walks into the trap above you and hits the trap right in front of you, deploy another one in the same spot facing the same direction and wait until that enemy is dead. Kill off everyone else and when the mission is over the achievement will unlock.