Ever

When Dyon conquered his second sky castle, aside from the green-armored guardian, most of the things he gained were absolutely useless to him. Many revolved around taking control of beasts much more powerful than yourself, but since he had Biibi, Sen, Shere and Linlin, he didn't plan on doing so. At least not yet. Because of this, he planned on handing off much of what he gained to Ri. But, there were two things he set aside for himself that were extremely useful.

The first was a beast controlling formation compendium. This compendium gave detailed information about the best and most effective formations for absolute control over beasts, covering practically every Common, Earth and Heaven Grade beast to ever exist.