Multitasking was nothing too difficult for a cultivator, but if one wanted to develop two high-grade secret techniques to their maximum limit, that was difficult to do.
Ling Han began to study the Earth Overturning Seal first, aiming to reach the point that he would be able to use it single-handedly.
The difficulty of this did not originate from the moves, and in truth, Mystical Powers did not have any moves per se—that was the case with the four Mystical Powers Ling Han had learned to date, at least. Instead, Mystical Powers merely taught you how to circulate your Origin Power so that it would adhere to some specific pattern, but exactly how one was to put it to use was entirely up to himself.
For example, in the case of the Earth Overturning Seal, both hands would be covered fully with unique patterns—the formidable power of this Mystical Power originated from these patterns as they possessed incredibly terrifying destructive power.