In "Beast of Reincarnation," there is a wide variety of powerful weapons, and Skyfall Thunder is one of the most effective ones. To obtain Skyfall Thunder, go to the inner hall teleport point in the Ruined Tower located in the Giant Tree Area of the Sunken Region. After exiting the teleport point, head upward and defeat the Key Guardian Golem above to acquire Skyfall Thunder.
How to Obtain the Skyfall Thunder Weapon in Beast of Reincarnation