Judging by the page on the left showing DF banners for various duties I think this is a new system to encourage players to go back and replay old content. If I were to guess at the mechanics, it would appear that the various duties offer special quest item rewards (those items pictured down the right-hand side) that give a different overall reward based on the combination you create (that connect four style grid on the top-right).

It looks interesting for sure. Curious what the actual rewards are.