malachite wrote:This begs the question: What does the "Shared card" feature actually provide? How does this affect DeckBox functionality?
You mean the "i share cards between decks" flag? It does not change any functionality directly, but the counts are shown in a different way (for example "count of this card in all built decks" becomes a max between your built decks instead of a sum).
But it does make for some "guesses" to be clear though, since if you share cards between decks, and you have 4 mountains in inventory and 3 in a certain deck, it is crystal clear you need another mountain.
Your example, without "sharing between decks" when you have 4, 4, 4 in decks, 11 in inventory, you don't actually know where exactly is the "missing" card... in which deck is it missing? Not clear, and with the current system you also can't actually specify. 