The treasure that could seal a seventh-tier space was incredibly rare.
Even Zi Liyuan, that fellow, had never obtained one.
Therefore, he was completely unable to seal the space to restrict the old witch.
The only way to defeat her was to engage in a consumption battle, depleting her power in the King's Domain, grinding her strength down to the next major rank, regressing to the sixth tier legendary level.
Otherwise, with Zi Liyuan's current methods, even if he went all out, it was impossible to easily slay a seventh-grade sanctum, unless the opponent recklessly fought to the death with him.
Now enveloping the entire city in the Death Domain was merely a temporary measure to ensure the old witch wouldn't escape outside the city.
Once she tried to escape, breaking through the Death Domain's blockade would reveal her position and direction, making the pursuit much quicker then.