Laying the formation indeed wasn't an easy task. This formation had to envelop the entire Stellarsky Domain. Hence, when Jiang Yi told the elder their decision, he immediately made Jiang Yi go and prepare the things he needed.
The materials were very complicated and numerous. Fortunately, after consulting the Buddha Thearch and others, they all realized that each of their clans had a few. Once they headed back to their cities, it shouldn't be a problem.
Time was of the essence!
Besides the Saint Empress, Jiang Yi teleported the Buddha Thearch, Yin Thearch, Tang Shenji, and the various clan heads into the Mystic Divine Palace as they flew south as fast as they could. Once they could use Heaven Evasion, they would be able to reach the North Thearch City within two days!