This solution is only for those with 2 computers (Windows 8.1) .
* Defeating any monsters by any means - dynamite, machete, or arrow will count towards this achievement.
Both primary and secondary computer must be running at the same time.
1.Sign on your primary PC. Find a level with lots of monsters. Progress into the level and make a save convenient for you. Quitting is not require for saving. Performing any action (flagging ,moving adventurer, etc) in the game will automatically save to your cloud.
2.Sign on your secondary PC and load up the cloud storage.
3.On your secondary PC, defeat all monsters and fail the mission. Go back to homepage.
4. On your primary PC, perform one action to update the cloud.
5. Load up cloud storage on your secondary PC.
6. Rinse and repeat steps 3 -5.
*You must lose/fail in order for the stats to count. Exiting the mission will not update your statistics.
* Any monsters killed at any point of your save will count. I defeated 1 monster in cloud and 1 in local. See the end-game statistics in the video.
* The achievement should unlock in-game when you defeat your 100th enemy. For some, it may unlock after you failed or completed the level.