Deck compatibility
The decks you build can be used in 3 gameplay modes : Single player (both quick fight and campaign), Ranked PvP and Open PvP. A single deck might not be compatible with all 3 gameplay modes at once, however.
In Single player, you may use both normal and upgraded cards, but you can only use those cards that you have unlocked yourself thus far.
In Ranked PvP, you can use all normal cards in the game, even those you haven't unlocked yet in Single player. Upgraded cards are not available in this mode and some cards are 'restricted', this means that they may only appear a certain number of times in a deck.
In Open PvP, you may use both normal and upgraded cards, but you can only use those cards that you have unlocked yourself thus far.
The deck manager (accessible from the main menu) will aid you in keeping track of which decks are valid for these gameplay modes and will also tell you why a certain deck is not compatible with a certain gameplay mode.
When you open the deck editor from within the quick fight or campaign modes, you'll only be shown the cards you have unlocked thus far, so you can't accidentally make incompatible decks this way.
When you open the deck editor from within the deck manager, an additional button will be available to restrict card amounts to Ranked PvP. Clicking that button will cause the deck editor to show all cards available for Ranked PvP with their restriction status taken into account (if any).
In case of Ranked PvP, a deck that contains upgraded cards might still be available for ranked multiplayer duels. If you select such a deck for Ranked PvP, the game will temporarily change all upgraded cards into their normal versions for the duration of the duel.