Yuan Longshan had miscalculated with Han Zheng, he never anticipated that Han Zheng would be able to produce one after another of Xuan Gang Realm cultivation techniques.
The realm of a cultivation technique simply meant that only upon reaching that particular realm, one could unleash the full potential of the technique.
For instance, the Great Vajra Ming King Seal that Han Zheng used was of the Xuan Gang Realm.
In fact, only upon reaching the Xuan Gang Realm and being able to externalize Gang Qi could one truly condense the Vajra Ming King Avatar and bring out the full might of this cultivation technique.
Therefore, many Xuan Gang Martial Artists were still using Innate Realm cultivation techniques, rather than completely discarding them once they had reached the Xuan Gang Realm.
Moreover, each level higher in cultivation techniques meant an increase in rarity by tenfold or even dozens of times.