I was inside Fao Fortress near Flag E on Conquest and was killed by a player who was completely INVISIBLE. The game didn't render the player who killed me or he was hacking somehow. It was annoying as hell and I recorded what I saw on the Xbox Game DVR but have no idea how to upload to Youtube or this forum.
What happened was I was shot once from behind while I was running inside the fort toward the doorway at flag E. When I turned around only a teammate was there and I ran behind him to see if anybody else was there and there wasn't. I double checked my health and it had gone down by a third so I knew an enemy was around. I went into the first alcove on the left and nobody was there, I turned around and was clubbed to death. The kill cam then shows the gamertag and the melee club weapon used and is following somebody who is invisible and can't be seen! Very annoying!