This can be won at any point in the game, not just during the DLC. For me, I use the Northern Realms deck. I obtained as many cards as I could and had the leader card Foltest The Siegemaster equipped. This allows me to double my Siege unit cards for a round.
As I play, I always put down all the cards I can in the final round, even if my opponent has already Passed. This allowed me to get a score over 190 in the final round. I had double put on 2 rows and had stacked as many cards there as I could. If you play gwent whenever there is a new opponent, overtime you should have enough of a chance to get this one.
Cards with Tight Bond on them also help. These are the ones with the handshaking symbol. I have 3 "Crinfrid Reavers Dragon Hunter". They are worth 5 points each, but if you get all 3 in your hand, they are worth 15 each, so 45 points. Then put double on that row and you have 90 without playing any other cards. There are 2 siege weapons that stack worth 8 each, so they could add another 32 each if both played and then doubled. So if you happened to have both of these stacks, that is 109 already.
Spy cards also help for this as you can gain more cards with them which helps. It is especially good if your opponent plays them too so you can use a dummy on them to gain them for your cards and play them to get 2 more.
Basically, if you don't Pass as soon as you win the final round, you should get this over time just playing.