GWENT: The Witcher Card Game

This is much easier to achieve during an Arena special event.

I unlocked this during the Monster Faction Week special event which only allows you to pick Monster cards for the deck. This increases your chance of getting three of the same card as you don't have to worry about the randomness when all the decks are available to choose from.

I'm not sure how often these faction related events happen but if someone finds a calendar online let me know and I'll add it to the guide.