Fracture

This can be a difficult achievement to unlock, especially on Hardcore, as the beam has to kill the enemy while they are under the effects of TD. Simply knocking them in to the beam is not enough.

Now, there are many areas in Act 3 where you can unlock this, all in the same chapter: Genetic Beams, however, one of the locations is MUCH easier than the rest. This is the third beam location. You will know it because:

a) You have to divert the beam around some debris rather than just lowering the debris.
b) There is a Data Cell under the end of the beam that opens out in to the central chamber.

When you are in the correct place look for a Lodestone. This is the key to making this easy. This is what you should do:

1) Kill all enemies in the room except one.
2) Create a gully along the beam. What i mean by this is that you should raise the ground either side of the beam and leave the center lowered. (It will look like a half-pipe when you stand looking along the beam)
3) Shoot the Lodestone in the center of the gully, this will draw the last enemy to that spot.
4) Raise the terrain using TD.

Now, due to the gully the enemy has nowhere to go but directly in to the beam. After about 30 minutes trying at the first 2 locations, i did this within 3 minutes here.

Hopefully this should net you this tricky achievement.

This is a very tricky but easy achievement ok i got this on the genetic beams chapter first kill almost all the enemies and then leave one to use for the achievement

after you do that try not to get killed and it does not matter if the beam is restored or not because you will be moving the terrain around a whole lot but what you do is you make him get into the beam several times to damage him and after a couple of times he will die the next time but you do this bye using the terrain to make him jump into the beam or rise into the beam you have plenty of chances to do this

This can only be done in Act 3- Genetic Beam. When an enemy walks under a beam, use RB to raise the terrain underneath him and the beam should kill him. This could take several tries.