Leader cards add the extra punch to your Gwent decks, so choose wisely. In The Witcher 3: Wild Hunt, there are 4 leaders for each faction, with 4 more added on with Hearts of Stone. With Blood and Wine, 2 leaders are introduced for the Skellige deck. Be aware that the last leader cards of each faction in the base game can only be obtained through the gwent quest, High Stakes, by beating each opponent.