Higher domains
At first glance one would think that all domains were equal but like all things in the world that simply isn't true. Some domains are simply more important on a reality scale such as space and time. Many domains relied on these two in order to even exist after all. Creation and destruction were two domains that actually consisted of multiple other domains in a sort of overarching umbrella domain. Magic , souls , fire , weather and lightning were all domains that fell under destruction which barely qualified Nick to attain it upon his apotheosis.-
In the same vein magic , souls , crafting , language and weather were domains that fell under creation which made Nick more in tune with this domain than the other. Nicks bird and hunger domains were the only two that simply didn't fit in his general domain scheme. One would think the hunger domain to fall under the destruction domain but it was actually under the nature domain alongside the bird domain. Despite this Nicks attainments in these two domains was shallow at best as he had never bothered to spend any time on them so he was unqualified to receive the nature domain as well.-
This transformation to a higher domain was actually an innate trait that all beings that weren't born gods have upon reaching divinity if they have multiple domains under a greater domain. The reason for this was because of the world itself balancing things out. Born gods were tier seven right away and as a result had no time at all to really build up mastery of their domains before ascending. Apotheosis was not a simple process and upon achieving it all of ones mastery was "judged" for lack of a better word and rewarded by the world accordingly. -
Without any mastery of their domains since they were born gods they got no rewards as in many ways simply being born a god was reward enough. Having higher domains didn't automatically mean that someone was more powerful than other gods however. That simply wasn't how domains worked but rather it was about potential instead. Regular domains only had so many possible ways to be mastered before they simply ran out of potential. A good example was the crafting domain that Nick and Hephaestus had. Even though the styles Nick introduced had major differences they also had many similarities. -
This applied to every crafting style he might get in the future as well which meant that at some point that domain simply won't grow anymore regardless of the effort put into it. Fire and lightning were the same in how limited they were. Higher domains like creation and destruction on the other hand were far broader in terms of potential because they held the regular domains that fell under them which was quite a long list. In other words Nick wasn't more powerful than Hephaestus and Zeus but he had more room for growth and power in the future.-
This was VERY bad news for Zeus as it meant that he was now limited in time as if he didn't manage to kill Nick before he can grow into this potential it was game over for him. The problem came in the form of Nick being damn near impossible to kill thanks to being bound to his realm. Speaking of the realm Nick no longer needed to keep the ring that housed it on his person to freely access it. This meant he had been able to hide away the only weakness he had far from Zeus's perception.-
Unless Nick was stupid and brought the god into the realm he was effectively immortal in the truest sense of the word. Zeus didn't know this though and while he repaired and honed his power over the last two years everyone else in the world wasn't idle either. No new gods besides Nick had appeared but a few new tier fours and fives had shown up. There was even a couple tier sixes in the form of the Flammels that had become prominent. On the list of tier fours was unsurprisingly Snape who was only lacking in pure mana to reach that point previously.-
What was an unexpected addition to that list was Hagrid whose giant blood had made him grow in pure power after the ritual had finished and over this past two years had broken into tier four just based on his own knowledge and mastery of nature. Dumbledore had become tier five as well but that was honestly to be expected. The biggest improvement however was Celebrimbor who had endured Nicks tough teaching and made great strides over the last two years. He had grown to tier four but had fallen in love with the subtleties of magic and thus tended to obsess over the things he didn't know about it rather than work on advancing his power.