Legacy of Darkness is a Booster Pack that combines the Japanese sets Struggle of Chaos and Mythological Age. This series was released in the Yu-Gi-Oh! Trading Card Game in English and in the Yu-Gi-Oh! Official Card Game in Asian-English and Korean.
The Spirit monsters were introduced to the game in Legacy of Darkness, along with many Warrior, Dragon and Fiend-Type monsters and support cards. The set of 101 cards is comprised of two Secret Rare, 10 Ultra Rare, 10 Super Rare, 17 Rare and 62 Common cards, with "Yata-Garasu", "Dark Ruler Ha Des", "Exiled Force", "Airknight Parshath", "Fiber Jar", "Bottomless Trap Hole", "Royal Oppression", "Injection Fairy Lily", and "Last Turn" being the most desirable.