[Collection/Filter] Filter out cards that are in a deck.

{"ops":[{"insert":"Not the original poster, but I can. I’m just getting back into Magic after many years and have one precon and a bunch of old cards, plus some new acquisitions. I’ve digitized my entire library, but not before wrangling 99 into a really lousy “jalopi” of a Commander deck. It needs an overhaul, but I don’t want to steal from my precon to do that.\n\nI also do a bit of programming, and this process should be pretty straightforward. Just add every card in the collection to a hashset where each element is [name, block, card, quantity]. Then, for each card in the deck to exclude, match against [name, block, card] then subtract [quantity] from the hashset entry. The result is a complete list of cards not in a given deck. This could be repeated for arbitrarily many decks. You’d be looking at a worst-case time complexity of O(n^2) and an average time complexity of O(n), where n is the number of cards in the collection. Even for a collection with 10,000 cards, you’d be looking at worst-case roughly 200,000,000 operations, so maybe a second or two to complete, and RAM consumption of maybe a few megs.\n"}]}

{"ops":[{"insert":"Not OP, but i can explain the need because I've been looking for this feature.\nI have a decently sized digitized collection and a few decks and precons, therefore, when trying to build a new deck, knowing if cards in my collection are in a deck is majorly helpful.\n\nTo this extent, filtering for cards in a specific deck (presuming multiples of this filter can be stacked) would work great as it would allow only looking for cards in / not in a set of decks I care about especially.\n\nThis would be even more useful if such a filter would be available in the local in deck filter to compare and verify decklist overlap, but understandable if not possible. \n"}]}