The premium site has the "Built Deck" feature, where cards are counted as "in use" in your inventory. Normally, when you're building a deck and list more copies of a card than you have available, there's a red shading that alerts you to the fact you don't have enough cards. But if, say, I have only one copy of a card, and try to use it in two different decks--even if one or both are marked as "Built"--I never get the warning. This happens regardless of whether or not I have "I am sharing cards between built decks" checked in my settings. I find this really obnoxious as I'd love to be able to use the site to e.g. plan what singletons go into what deck or cube.

Is this a bug? Or am I doing something wrong?

I would submit a report of this through the "Support and Feedback" section. This used to work for me exactly as you describe, at least when I had premium previously.

I have not had premium so I can't speak to that.

But in regular deckbox 'in-use' cards only count between the main deck and sideboard of a single deck. It has never reached across multiple decks in the way you describe, for me anyway.

zga wrote:I have not had premium so I can't speak to that.

But in regular deckbox 'in-use' cards only count between the main deck and sideboard of a single deck. It has never reached across multiple decks in the way you describe, for me anyway.

If you have premium then you can turn off the option that says "Share cards between decks" and then it will work like described above. It will count only cards in built decks and will consider both sideboards and main deck cards.