The twelve Zodiac Stones were created when the twelve disciples infused their magic into the stones that were gifted to them by the gods. The power of the zodiac stones was not to be used until a true successor was found. Many had tried to become the wielder of the stones but had failed, like Rashidi.
However, a successor deemed worthy of the stones was found during the Xenobian Rebellion, in Destin. He was granted the Tablet of Yaru by the goddess Fellana which he used to collect the twelve stones from the messengers of the gods spread throughout Xyteginea.
While powerful, the twelve stones are matched in power by the thirteenth stone, the Black Diamond and the symbol of bravery, the Fireseal.