Magicka

Start vietnam map, take the m60 from the USA soldiers at the begining, and then create earth barriers (e+d then shift+right clic) and destroy them. Spam and detroy, repeat until achievement pop up. This method is faster than others, because this blocks count as 2 kill each one.

In order to obtain this achievement, you need to kill every enemy. so don't leave the place before you earn the achievement.

They come lot of enemies so i used my best combo: QRQRESA then Shift+left clic (you charge it in the sword), then Shift+left clic (now you throw the magic)

the best place to farm this is in act 3, in the first door on the left. You need to kill one big monster then you can farm infinite murlocks. i used the combo (QFQFSAA then shift+right clic)