Wallhacking initially, then turns on the damage mod and seriously cheats his ass off. 

11:2 from 11 hits for 1 kills/hit with MX4.  http://battlelog.battlefield.com/bf4/battlereport/show/1/906840866848412544/1774704311/

26:6, from 50 hits for .52 kills/hit with MX4.  http://battlelog.battlefield.com/bf4/battlereport/show/1/906838443631219584/1774704311/

And here's the spectated video of that whole game...  https://youtu.be/wMuX83qOKHQ?t=33s

- :44 notice he looks left through the wall as he heads outside and at :48 he starts firing at the rock.  Enemy player doesn't actually appear until :52 (and even with the wallhack, our hero manages to miss the guy and dies himself).
- 2:01 he's aiming and firing at a barrier with no player visible and is so focused on that he ignored the other player running left to right (and again dies).
- 2:25 immediately after he spawns he "sees" the player through the left wall and turns to
 go back and get him.
- 2:55 as he heads outside, he "sees" his opponent through the wall.
- 3:15 he dies another ridiculous death, and doesn't respawn until 4:05.  He's adjusting his cheat settings.
- 4:19 he sees Verta-Cobra through the floor and snap kills him and then...
- 4:25 LOL.  Instakills 2.
- 4:50 Shoots at the wall a lot.
- 5:06 Looking through the mountain at players.
- 5:15 Sees enemy in the cells and heads in, preaiming and prefiring.
- 5:35 to 5:58 full retard cheating.