There have been some issues concerning the promo codes interacting with certain platforms. While I can’t go into detail, I can tell you that these problems forced the Duels team to delay promo releases to the public on very short notice (which is why you didn’t see PAX Aus and SDCC attendees talking about them). I apologize for the frustration that this caused for those eager to receive word from the attendees at those events.
The good news is that the following promo codes are now available for use on Steam, PS3, and Android! Each code will unlock a new promo card for each of the 10 decks. Unfortunately there will be a short wait before these first couple codes become available on Xbox (codes will be enabled soon for you to enter and I'll update this thread when that happens) and iPad (promo cards will be automatically unlocked following an upcoming patch). Sorry again about this delay. We really appreciate your patience in the meantime.
Promo Code #1: GKSNDR
Promo Code #2: DWNNDR
EDIT: Steam users, having some trouble getting promos to accept? See this post later in the thread.