Trek to Yomi

During chapter 2 you will reach this cave area. When you see the location above, climb the ladder on the left (in the center of the pic, since it's kinda hard to see) and go through the doorway. You will now be in an area with enemies below you, walk over to the rope and cut it dropping the crates on the enemies and killing them.

Restart the checkpoint and repeat until the achievement pops

At various points along along your journey you will encounter some enemies standing around an environmental hazard, such as bandits talking underneath a hanging wooden pallet or enemies standing in a stream in front of a dam. It's generally pretty obvious when this is set up. There will be a short alternate path around the enemies that will lead to one or more interaction points where you can do something to trigger the hazard and kill the enemies (generally by cutting a rope with your sword.)

Trigger the hazard and wipe out the enemies. Get 10 of them this way and the achievement should pop. I missed some of the hazards and still got this before the end of chapter 4 when I triggered the dam burst there, which kills a bunch of enemies.