Diamond Queen into DIamond King is the hardest scenario in this game without a doubt.
However, the fact that you know at the 3rd Queen that Diamond is coming up, should signal to you, that this might get tough.
I usually like discarding clubs, since their use imo is very limitted and in fact sometimes counterproductive (slow rounds). Imo you want to value Clubs higher in this case, especially if you can combo them (usually with Spades), and, this should go without saying, never go into it without full hands, every card counts here.
The difficulty is, that this scenario demands all colors. You want spades to reduce attack, you want clubs to get through the fight quickly, since you can't just draw into more cards and you want diamonds, because you'll need to draw once you're done with the diamond enemies. That leaves hearts out. The only flexibility would be good discardpile management leading up to this situation, so if you have a decent tavern and the discard pile isn't too big to handle, imo that is where i'd be a bit more liberal with discarding hearts. If that isn't so, try to finish with hearts so you can get a decent draw to recover.
All that said, you are still subject to draw luck and sometimes you are just not in a good situation to handle the fight, like when you go into the diamond queen by drawing and only draw small value cards. It happens.
But when starting out, this scenario was pretty much a loss. Having played a lot now, i'd say my chances are usually pretty good.
If you get this far, you already had some time to manage your hands.
