Kill 30 enemies by using the grappling hook and making them fall to their death.

To make an enemy fall to his death you obviously need to pull him down from a high point. To pull an enemy down you need to aim at him and tap the button, this will attach the grappling hook to him and pull him forward.

Some good situations to get this are as follows:

1. When doing a stronghold takeover There will be enemies in the towers with rocket launchers or sniper rifles. Just pull them down and they will die every time.

2. When killing colonels Some colonels are on roofs of buildings and are surrounded by normal enemies. Try to focus on these and stay near the edge of the roof, then keep whipping them and some will fall over the edge.

Look for the Fall Kill to confirm you were successful at making an enemy fall to his death.

NOTE: This is sometimes glitched but in a good way! For example, if you constantly whip an enemy towards you at ground level (on a road) this will bring his life down bit by bit. If the last whip happens to kill him then it sometimes counts as a Fall Kill.