Where Duress really shines is against opposing combo, prison, and the card Counterbalance
Amber has established itself as the best colour for getting your vital character cards back out of the discard pile, but this is the first time weve seen a card bring your characters from discard straight onto the playing field
That makes them a considerable mana cost to play, but are worth it in the long turn
Thats pretty much all you need to know: Cast a bunch of creatures, attack early and often, then save some of your cheap proliferation to accelerate to the finish line
Similarly, permanents that phase out with counters phase in with those counters
Why would the Wizards print such a strange counter-productive card is beyond anybodys understanding today