Have you tried the Classic 6 v 6 playlist, played a combined arms match, and still not unlocked the card? Some of the maps that were exclusively combined arms maps prior to TTK are now circulating through control and clash matches that are not explicitly combined arms. If I am not mistaken, you can tell the difference in the wording appearing on the right hand side of the screen, above the weapon load out panel that runs along the bottom. Edit: I meant to say the wording is above the team scores panel on the right hand side of the bottom of the screen. Sorry for any confusion.