Fury Unleashed

** Due to the game being a Rogue Lite I cannot give an exact location to get the achievement ** however I can give you the method I used to get the achievement.

Method :
The best method is to choose all the grenade upgrades and health upgrades for your hero. I demonstrate this at the start of the video.
Once you start kill every enemy with a grenade until you have none left. Only open up ? drops after you have no grenades left as sometimes these hold special grenades which will re-stock you.

After every few kills the enemy will drop a grenade due to the powerups chosen. As soon as you have grenades restocked keep killing more and more enemies with them. The easiest is to run close to them and push LB facing them. You can also often get multi kills which makes this quicker. You need to be able to get to the middle of comic 2 to have killed enough in one run to get the achievement. This can take a few tries , so be patient.