Because providing direction and guidance on Spirit Runes was already a part of the basic course for the second year at Saint Byrons, "Fundamentals of Spirit Rune Theory (Intermediate)," the "Book of Wild Thunder" was lent to Shard rather than sold to him.
Just like "The Mad Light Chaser," Shard needed to return the book after obtaining the Spirit Rune or buy it himself at a high price.
Besides guidance on Second Ring Spirit Runes, Shard also applied to the Academy Library to learn a specific Arcane Technique or Sorcery for detoxification, which should be effective not only for himself but also in treating others. During the upcoming second cocktail party, he planned to sample the Deity's Blood Brew, and Shard was not confident he could withstand it.
