Amnesia: The Bunker

Whilst walking through the bunker, you'll run into gas grenades. To get this achievement, you just need to lob one of those into the creature and have the gas hit it. Alternatively, you can lure the creature into a gas grenade trap and have it take damage. I managed to get this in the first room of the Arsenal, by tripping a gas trap then having the creature step into the gas cloud.


If you do this, you should also get


Good luck!

Edit: I've found a more consistent way of doing this. In the prison, when you open up the german prisoner's cell, the beast spawns consistently on the cell opposite to it, because of all the noise. I've had three playthroughs where I did this, at least, and on every single one the beast spawned inside that cell. What you can do is toss in a gas grenade (be careful to not aim into the hole or it may fall off of the map), then go back to the control panel and open the cell. The beast will crawl out, take damage and go right back in.