parkerlewis31884 asked: From Matt Tabak on reddit : "Mark is incorrect here. Contraptions are not legal in Legacy, or any other format that doesn’t include Un- sets. They don’t have Magic card backs, and they aren’t DFCs. I will try to get him to clarify."

Matt is correct. Anything without a Magic back or a double-faced card is not, in the current rules, legal in Legacy.

If Contraptions are a giant hit and years from now we cards that assemble them in black border, as the Contraptions don’t have a silver border, we have the option of making them Legacy legal.

But right now - they are not Legacy legal. Note that the point is moot as there’s no way to get a Contraption onto the battlefield without assembling it from the Contraption deck.