I tested every fraction in the game for this trophy. The best one is Nilfgaard, then
Northern Realms then Monsters. I tried multiple strategies from all over the internet (youtube) but eventually I came up with my own. It's best if you do this achievement after completing the main story so you already have a strong set of cards. "Hearts of stone" cards are additional. It's possible to get a large number of points without them but they are very helpful, so if you own these cards I suggest putting them in your deck. I'm playing on normal gwent difficulty but I don't think it really matters because this strat is OP. Hope my guide helps 👍

• Leader
  
  
  
  
• Close Combat Cards
  
  
  
  
  
  
• Ranged Combat Cards
  
  
  
  
  
• Siege Cards
  
  
  
  
• Special Cards
  
  

The strategy for this deck is to have as many cards as possible in one hand and to make your enemy go bankrupt. It's important to have atleast 1 spy card at the start of the match so if you don't get any, you can give up already. In order to make things right it's best to either win-lose-win or lose-win-win, although I had matches when I won 2 times in a row and ended up with a score over 187.

https://www.youtube.com/watch?v=7saYEuy4ejY&t=9s

Here is a screenshot of my highest score I got using this method!