Workshop Crate #1
The first community-created mystery box is now dropping as the January 2017 Workshop Crate #1! All of the contents were voted on in the curated workshop, and are the first time you can get mythical variants of workshop items!
To open a workshop crate you will need the associated workshop key available from the stockpile. This is because the sales of the special key are split with the creators of the items in the crate. Future non-workshop mystery boxes will continue to use the normal mystery box key, however.