Resident Evil Revelations 2

an easy way to get this along with several other achievements is once you place the cog in the wall near the end of claires mission, an infinite spawn of afflicted will appear. They will come two at a time.

I got the flashlight achievement, followup achievement, crowbar achievement, physical attack achievement, 100 knife kills achievement, 100 afflicted achievement in about 20 minutes.

Also for barry, there is an infinite spawn of revenants at the end of his mission. After you knock down the gate with the crane, revenants will appear two at a time. Just keep shooting them until it pops, and DO NOT go close to the gate or a cutscene will appear and mission over.