annorax asked: Black border Contraption assemblers could not get Unstable contraptions in the tournament formats where border colors matter, because Unstable is not a legal set in any of those formats. Black bordered Magic with Contraptions would be completely safe from Unstable.

Being in Unstable doesn’t make something illegal in tournament play, the silver border does. The basic lands and Steamflogger Boss, for example, are playable.

If a black border card let you assemble Contraptions, you could assemble any Contraptions you liked. Remember that what’s legal in your normal deck is also different than what is legal in your Contraption deck.

There are no tournament rules for outside decks yet because no black border card that goes into a deck accesses any. Yet.