There’s a glitch in Battlefield 4 which allows the player to exploit the ability to combine two classes and use the skills of each.
The glitch is confirmed to be working on Xbox One and possibly on PC.
It was discovered by Battlefield Central, and at present there’s no word on whether a fix is in the works.
Hopefully, DICE will kill it soon.
In the meantime, if you want to know how it works, head through the links.