We knew that four-color decks presented a special challenge for getting access to all of your colors of mana, so we spent some time identifying rare dual lands that we didn't think we'd want to put into booster packs in the near future
Then exile it.) Illustrated by Greg Staples Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp

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I would be very surprised if the numbers are over 5k, but my guess is as good as yours
Some tools even let you track the prices of entire booster boxes and analyze their expected value (EV)