I was doing cabal extermination missions with another cabal member.
On one mission, the following happened: I got to the starting point of the map, my cabal member did not because he experienced a crash. Now I was on the map, but my avatar was invisible. I was able to move and shoot, but I was not only invisible, I was indetectable, i.e. the enemies did not react to my presence or to my shooting or to their fellow cultists being blown apart.
It was a wholesale slaughter and I was able to finish the mission alone with 4 minutes left.
Nice experience, burt that is not as it should be ;-)