This is the part I love the most. To create the prototype, I simply cut 8 cards per hero and wrote the card rules on each of them. Then I created the various tokens needed and used 4 miniatures to represent the heroes.
I also used dice to keep track of the various numbers going on in the game and colored cardboard on which I took various notes related to the heroes during the gameplay.
Each hero's deck was designed to create a compelling experience with just a few cards. We will learn later about balancing and how to set up every number and variable in a game: