For this achievement you must attain a multiplier of at least 10. This achievement can be tricky, as the time-frame between each kill is very small. You must act quickly to attain a multiplier this high. Start a level with more Hunter Generators. Destroying Hunter Generators can increase your multiplier much quicker than killing regular hunters. After reaching 10x multiplier, the achievement will unlock.
A good stage for this achievement is Chapter 6 Stage 1. The top left corner has multiple Generators, as well as multiple enemies. Grab the Freeze Power-Up in the center of the stage, and immediately run toward the Generators. Destroy the Generators, kill the remaining trappers, and the achievement should unlock. (This may take a few tries until you get it down to a T.)