As it would be dangerous for any youkai to defeat the Hakurei shrine maiden, many youkai felt that their existences had become meaningless. Thus, the Spell Card Rules were introduced. The spell card rules allow both parties to show off their skills in a beautiful display of dueling power. The major points are:
* Spell cards are special named techniques, the use of which requires a declaration of intent.
* The number of each parties' spell cards must be determined in advance of a duel.
* The first party to use all of their spell cards must admit defeat.
* The victor is entitled only to what was agreed upon before the duel. If they're not interested in what their opponent has to offer, they can refuse a duel.
* Winners should generally allow losers a rematch.
* Unforeseen accidents should be resolved in some fashion.
Following these rules allows for conflict resolution dueling which is almost like a sports event. With the introduction of these rules, it became possible for even relatively weak humans to challenge youkai. At the same time, it became possible for youkai to safely defeat the shrine maiden without worrying about the consequences.