Black Cards.
Privately customized Spirit Cards that had never been officially registered and bore no Card Maker's signature.
Black Cards were not illegal Spirit Cards. The Seven Towers Federation had no such concept as illegal Spirit Cards. Black Cards were more like products with no guarantees or other protections.
Once sold, no responsibility was accepted.
"Double-sided cards... are actually fairly simple." While Xiao Yi formulated a repair plan, Duke studied this 2-Ring Black Card—Heart of Perdition.
There were many types of Spirit Cards.
Single-sided cards, double-sided cards, layered cards, nested cards, cluster cards, irregular cards, three-dimensional cards, and countless others.
The most common were naturally single-sided cards. Most 1-Ring Spirit Cards were single-sided.
Only after reaching the level of 2-Ring Spirit Cards did other card-making methods become more common. The Heart of Perdition Black Card before him, for example, used a single-ring, double-sided entangled design.
Ordinary Card Masters hated this kind of design.
It was not because the design was overly complicated, but because repairs required constantly switching back and forth between the two circuits. It was like frying a pancake and having to flip it over again and again. If even one step went wrong, everything had to be started over, making the process tedious and exhausting.
For Duke, he only needed to leave the steps to Xiao Yi.
It really was simple.
He carefully began the disassembly, taking apart the card surface, card material, and card core in sequence. Then he used a ring-pulling instrument to pull out the spell models from both sides of the Black Card, which looked like a twisted mass of tangled hemp.
With Duke's current Spiritual Power, finding every break in the middle was honestly beyond him.
"Master, turn it over. Start with the first break node on the rear circuit." Xiao Yi