I took a peek at the Review tab and I noticed this:
I love the idea of badges unlocking certain features. Do any other badges do this? I think it's a great way to deepen the engagement of badges.
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That is the unique badge that requires you to first have another badge, to be able to gain it. There are other badges that you gain after you gained another badge, such as the Copy Editor that is gained after the Strunk & White, but in those cases there isn't an explicit requirement to gain first one, and then the other badge.