you draft a deck for your opponent

best part is youll need to think about which cards are the worst for specifically the deck you are making, but also hardest to cast, least useful in the context (all noncreatures for example), or cards that simply don't fit at all in the context of the theme of the deck

gets harder & harder the less cards there are since the best cards will be last picks, which makes things v interesting

remember though, 15 of those cards can be chopped by the opponent, so ultimately they will be the ones using your pool of trash that you've given them to find any combos or synergies.

you could also play this cube normally and just try to draft the best possible deck you can from the worst cards imaginable