Yu-Gi-Oh! tells the tale of Yugi Mutou, a timid young boy who loves all sorts of games, but is often bullied around. One day, he solves an ancient puzzle known as the Millennium Puzzle, causing his body to play host to a mysterious spirit with the personality of a gambler.

From that moment onwards, whenever Yugi or one of his friends is threatened by those with darkness in their hearts, this other Yugi shows himself and challenges them to dangerous Shadow Games, which reveal the true nature of someones heart, the losers of these contests often being subjected to a dark punishment called a Penalty Game. Whether it be cards, dice, or role-playing board games, he will take on challenges from anyone, anywhere.

Each 5-card pack of Battles of Legend: Monster Mayhem contains:

• 1 Secret Rare
  
• 1 emblazoned Ultra Rare (always a Dragonmaid, P.U.N.K., or Orcust-themed card)
  
• 3 other Ultra Rares
  

Overall set size is 177 (52 Secret Rares, 51 emblazoned Ultra Rares, and 74 other Ultra Rares). 25 of these cards are also available as Starlight Rares.