East Sea Army vs Illusory Beasts, First Clash

Why is there a teleportation formation here? Is this perhaps something that the old man set up before engaging in the life and death battle with the Earth Immortal Realm Expert from the Blue Sea Empire, or is it perhaps something that was set up by someone else in the past and the old man just happened to learn about it?

Watching as the teleportation formation was slowly being drawn on the floor of the abandoned temple, Xuan Hao could not help wondering where the formation had come from.

If it did indeed come from the old man, it should have been set up years in advance, while if it had been set up by someone else, it left up the question of who would set up this kind of formation in the middle of nowhere for no discernible reason.