The Chronicles of Riddick: Assault on Dark Athena

For getting this one I hugely recommend Pitch Black mode.

Just become Riddick, and keep hunting people. Try to move a lot around the map, you are faster than anyone, so as far as you don´t run into a light or into a too open space, you can preety much obtain this achievement by just playing good in a match.

Try to search for lights, and kill people from the back. You have to touch them and spam RT to do this. If you think you are getting cornered (a light in front of you and another one on your back), try to hide in a corner, but don´t always play like that, because a idle Riddick is easier to kill than a moving Riddick that kills and run to the shadows.

Melee kill from behind is easy, just kill one from the back using this tactic.

For Melee double kill, just try to spot two people facing the same way. This is more common than you think, and you can easily kill both of them from behind if you are fast enough and they don´t hit you with the shotgun. You doesn´t need to kill them both with the same hit, just kill them really fast one after another.

Melee killing spree is easy too. Just keep surviving as Riddick, and you´ll get it in no time.

Remember: always search for lights, evade to touch them, try killing people from the back, and don´t stay too much on a place. With that in mind, this achievement will pop up in no time.