“Your move!”

Yugi Muto from the Yu-Gi-Oh television series is kind, clever, and values friendship above everything. While he lacks self-confidence, this disappears during a game of Duel Monsters1 because Yugi has a secret: within him lies the spirit of the ancient Pharaoh Atem. When Yugi begins a duel, this spirit manifests and Yugi Muto transforms into Yami Yugi, a confident and extremely skilled duelist.

In the first episode, Yugi uses his grandpa’s deck in a duel with Seto Kaiba, the regional champion. It’s not going well for Yugi, but he has faith that the deck will bring him to victory because his grandpa put his heart into building it. The battle evolves to a point where the outcome depends on a single card draw: Yugi wins if and only if his next card is Exodia the Forbidden One. Although Yugi has Yami Yugi on his side, he’s afraid to draw the card. Only when he remembers that his friends and grandpa are supporting him does he “believe in the heart of the cards” and gain the confidence to draw. Yugi reveals the card to Kaiba:

Exodia the Forbidden One

Did Yugi believe so strongly that he altered the physical card order in the deck or was he just lucky? Technically Yami Yugi has a magical power that lets him draw the card he needs, but believing in the heart of the cards is a theme that shows up in other, non-magical, characters too. We can better understand this idea if we consider the Duel Monsters game more broadly.

You can think of collectable card games like Yu-Gi-Oh or Magic as not one, but two games. The first is the actual duel where you attack your opponent with ferocious monsters to reduce their life points. The second game is that of deck building2. There is deep strategy in narrowing the ~8000 playable Yu-Gi-Oh cards down to a 40-60 card deck3.

Does your playstyle suit early aggressiveness or do you want to play for the long game? Do your spells focus on removing your opponent’s monsters or powering up your own? No matter how you play, the goal is to build a cohesive deck with cards that synergize well with each other.

Deckbuilding isn’t a one time thing. As you win, lose, and learn about new cards and strategies, the deck will evolve. I recently started playing Magic: The Gathering to join a tournament at work. In one game I found that my deck was weak against monsters with the “flying” ability so I rebuilt it with this in mind. The next game I was defeated by something totally different so I tweaked once more. My deck is the product of all experiences up to now.

This relationship between the deck and the duel is manifest in the relationship between Yugi Muto and Yami Yugi: While the shy Yugi Muto believes in the expertise and confidence of Yami Yugi to bring him victory, Yami Yugi believes in Yugi Muto’s skill to build a cohesive and synergizing deck he can use.

A diagram showing the relationship between Muto and Yami. Yami is in a section called 'Dueling'. Muto is in a section called 'Deckbuilding'. They have arrows labled 'believes in' pointing towards each other.

The Millennium Puzzle that Yugi Muto carries around his neck lets him transform into Yami Yugi and is a symbol of the deckbuilding process. It took Yugi eight years to solve the puzzle and unlock the Pharaoh’s spirit. Each piece of the puzzle symbolizes a Duel Monsters card, with the completed puzzle representing a cohesive deck. Just as a cohesive deck gives a player more confidence during a duel, the completed puzzle lets Yugi transform into the confident Yami Yugi. In scenarios later in the story, Yugi loses his connection to Yami, but the confidence and courage remain.

When Yami Yugi believes in the heart of the cards, he’s not referring to a magical force, he’s trusting that his friends, rivals, and Yugi Muto set him up for success, in deckbuilding and in general. It’s everyone’s dream to turn into an awesome alter ego during trying times, and Yu-Gi-Oh posits that even without a Millennium Puzzle, awesome alter egos can be born from the support and diligence of awesome normal egos.


  1. A card game between two players. Armed with a deck of monster, spell, and trap cards, each duelist aims to reduce their opponent’s life points to zero. 

  2. Dominion is an example of a card game that focuses on the deck building process. 

  3. \(\sum_{n=40}^{60}{8000 \choose n} \approx 7.40 \times 10^{139}\) lower bounds the number of combinations by ignoring the use of multiple copies of cards in a deck. In any case, it’s a big number.