Secret of the world
One should keep in mind that Nick had close to twenty two million people in his territory so the fact he could even get a mark to all of them in a months time was quite impressive. These were also nen constructs so nobody without nen could even see them which certainly didn't help matters. Still Nick activated his tithe ability again and drew even closer to tier seven levels of mana. The closer he got the larger and more sturdy his realm grew as well. One might question why merely collecting mana like this even worked to increase his personal stores and the answer was quite simple.-
It didn't , well to be more specific his current issue was that despite being tier seven he hadn't experienced having that amount of mana so his stores could only recover passively what he had experienced. By forcefully adding more mana on top of this amount his stores update to this new amount of mana for a lack of better terminology. This only worked because he should have more mana than he does by virtue of merely being tier seven but since he skipped tier six entirely he never got that mana.-
In simple terms Nick was playing catch up as a result of him taking a shortcut previously that screwed him over a bit. Thanks to his nen ability though he was making good progress on putting his mana stores where they should be. Add on the mana gathering array he had activated again and he was constantly making strides forward. During this process Nick worked to expand his realm via consuming entire uninhabited islands. He unfortunately had to break them down first as directly adding them to the realm would mean trying to bind the entire world to himself and wouldn't end well at all.-
Instead Nick first detached the matter from the world and then added it to his realm. No one was aware of this however as he was effectively eating away at the world to expand his power. This was obviously something that everyone would move to stop if they knew about. When it was mere truckloads of dirt and asteroids no one would care because those were things without any real significance but entire islands was a whole other thing. This was like someone ripping out whole mountains from the planet and there was only so many that existed.-
Still this ravenous devouring of matter caused the realms planet to explode in size as over the next year it grew to the size of Australia in terms of surface area. Once it reached that size Nick stopped consuming islands as it was now impossible for Zeus to outright destroy the realm anymore. While it was still possible for him to destroy it he couldn't do so in any amount of time that would prevent Nick from stopping him. The realms size increase was coupled with Nick finally equalizing his mana stores with his tier seven existence.-
The change was immediate once he did so as his power immediately skyrocketed and the his entire island became a mana void as every once of free floating mana was sucked into him to fuel this ascension. Within mere moments Nicks power went from the start of tier seven to the upper reaches of it as all his work on expanding his mastery of his domains caught up with him. Reaching out his hand Nick lightly tapped the air with an extended finger and the space he touched simply vanished , destroyed down to atoms in an instant leaving only a void behind.-
"That is rather concerning , are you maintaining the void there or is it simply unable to repair itself?" Hephaestus asked looking at the black nothingness where Nick was holding his finger. "It is constantly trying to repair itself and get filled in but my destruction domain is tearing apart everything that enters that area. At the same time I can do the opposite as well." Nick said and as if to prove his point a diamond the size of a softball manifested in the void yet still was surrounded by it at the same time.-
"In the beginning there was nothing and then god said "let there be light" and so it was that there was light. Destruction , the absence of matter and creation , the presence of it. I understand now." Nick said with a smile as he released his power and the spot he pointed at immediately returned to normal with a slight difference , there was a diamond that wasn't there previously. "Time , space and reality are the foundation. Destruction and creation shape raw matter and the rest of the domains give it function and substance. This is the secret of how the world functions." he said understanding the subject perfectly.