- **Setting**: An alternate world in the “Age of Arcana,” where magical energy takes the form of cards, and card masters control them in battle through mental resonance.
- **Core concepts**:
- **Crystal Vein System**: Magical circuits flowing through the human body that determine a card master's rank: Black Iron, Silver, Gold, and Legendary.
- **Phantom Beast Ecology**: Magical creatures ranging from F to SSS rank, which can be sealed into cards or fight as independent combatants.
- **Void Instances**: Randomly appearing battlefields in other dimensions, containing the legacy of ancient civilizations and rare card recipes.
