It was precisely because Zhou Tian's cultivation level had no difficulty in suppressing that rule projection that the abilities which had protected those living beings for countless years lost all effectiveness when facing Zhou Tian. Ultimately, when Zhou Tian intended to enter the opponent's base, he managed to do so effortlessly.
However, the fact that Zhou Tian could easily enter the living beings' base in the past doesn't mean that he can now easily enter the opponent's ancestral land. After all, compared to rule projection, rule avatar holds a completely unmatched power.
As for rule projection, it merely applies the power of the rule to that region. Although it still generates the power of the rule, since that power was maintained by other energies, it naturally caused the rule projection, while relying on the power of the rule, to have some effect. But in fact, the rule ability of those rule projections wasn't very strong at that time.
