Cards are an alternative to dice. Characters begin with three cards. If you are asked to play a card and have less than 4 cards, draw a card first. There’s no maximum hand size.
Impact on the game
Cards give the players more control over what checks they pass and thus more control over the game. Depending on the deck they also become a little game on their own, where player’s choices are guided by the cards in their hand (instead of the story unfolding).