Phantom Prospect Battletag Assignment

So with the new China Rising DLC for BF4 there have been a couple of new assignments. One of them is particularly mysterious, and that is the "Phantom Prospect" tag. The first requirement is to have premium, the second has a question mark.
To get this we presume that it has something to do with the chinese statues scattered round the new maps, that have brail at the base of their legs. But we can skip all that fun stuff and get to the nitty gritty.

If you go to the leaderboards there's a skull in the bottom left hand corner. If you click it it takes you to a pseudo login screen which then asks you for a password. the password is "bumpinthenight"
This unlocks the requirements for the tags.

Score 200 kills with Assault Rifles
Score 200 kills with Main battle tanks
Get a 300 meter headshot

The premium thing is not a hassle for me. But there's no way I'm ever going to get 300 300 meter headshots.  Oh well. +Andrew Runkle set me straight, turns out it's just a combination of all your head shots to make a total distance of 300 meters.

Update: So it looks like this dog tag is part of a larger easter egg. Check out Jack Frags video for more info on where it could be going.