Proximasaur

Once the god is powerful enough, they will leave their place of birth and begin a search for a world to inhabit, essentially bringing their own version of life to the world (whether it was already occupied or not). You could call this terraforming. Some gods may actually create a planet from scratch, or manipulate the system's star to be hospitable (or even create organisms immune to negative effects of others). Each god can be different, with their own rule sets for each world.

Gods can grow or lose their power, depending on how they manage it. Some powerful gods may occupy multiple worlds, even to the point of ruling an entire galaxy (and I'll extend upon that later). However, this can strain a gods power which tends to limit their capabilities and creations.

Gods ruling over multiple worlds are more likely to have fauna more like Earth's, limited to the universe's own rules (which godless worlds follow - at the moment I'm not sure if godless worlds containing life should exist or not).

A god(dess) like Nephi could be considered extremely powerful due to her ability to introduce magic into her world, however, Nephi only rules over one world, meaning potentially unlimited amounts of her power can be concentrated on a single globe and the extent of her actual capabilities is unknown.

As of Myth's current age, Nephi could probably terraform multiple worlds with the same rules as the original Myth (magic, multiple realms, creatures who wouldn't function properly on a world like Earth). But if she were to inhabit several dozen worlds, consequences and limitations would begin to appear.

Worlds like Myth would likely begin to collapse (magic systems would fail, Astrone would weaken and could possibly die, dragons and the alike would lose their abilities, and that's if the world itself is lucky. The non-living realms could destroy themselves leading to no divine realm and no spirit realm, just the original).

If Nephi were to stretch her limitations further, she would begin to lose power over multiple worlds, or risk eradicating herself (if not severely weakening herself to a point of inactivity - like a god in a coma if you will - this idea hasn't been explored enough to define).

Chances are, this will never happen, as Nephi prerfers to align with magical-fantasy systems.

To add to this specific goddess: Nephivia has no restraints against time and is able to see and influence the past, present, and future. She is an apathetic god who sets out stories for her creations. Some individuals have mass amounts of her attention set on them and experience more complex, eventful, lives, while all others have minor influence. She sets out their stories like an outline (she is not fully in control of their lives, only the potential events that are to play out - indirect influence), not everything can play out to plan (the astrone for example are less under her influence and some can cause unplanned trouble - she is more likely to communicate with them instead if she seeks their involvement, so she probably directed the astrone of tyranny "Poldra" to aid the celine known as Falcor).

Nephi would be labelled a goddess of time and fate (excluding Creation, her alternative title), but there would be plenty more out there with similar abilities.

What happens if two (or more) gods come into contact with one another?

This depends on the circumstances.

Sometimes, when searching for a new (if not their first) world to occupy, a god may encounter another. If the god decides to pursue the already inhabited world, it is highly likely to end in a fight, if not a war.

There are worlds out there that have multiple ruling gods (like how many mythologies have multiple gods except under myth's universe rules). It could be a cooperation between gods of multiple worlds, it could be a weird circumstance of 'sibling' gods, or maybe it could just be a cold war, etcetera.

A war between gods can lead to the destruction of another. They could end up weakened, or falling to defeat and loosing their own world, or they could be eradicated.

But the most terrifying situation of all is when two extremely powerful (galaxy-ruling level) gods go to war. For whatever greedy reason two (or more) gods of this level decide to fight, they risk the destruction of the entire universe.

For such power to collide would result in mass destruction, which would reach into further settings, affecting not just those involved, but other gods. These gods in their true forms are huge compared to those like Nephi. Think of two galaxies colliding, and while a collision in Earth's universe shouldn't be bad, in myth's it's like a trigger for the big crunch.

When a war between such powerful beings ends in disaster, it triggers the destruction of the entire universe, and upon being destroyed, everything is reborn all over again. A new universe, with entirely new gods and stories, only to repeat again.

This is important to prevent the universe from becoming crowded, as single gods in a galaxy of many are highly likely to become more powerful and occupy multiple worlds as time goes on, which increases the chance of galaxy-ruling gods to experience conflict towards others on their level.

To extend upon Nephi again: her power over myth is somewhat similar to the universe's rule of resetting. When events go out of hand and begin to go against her worldly visions, it is said that Nephi will reset her world all over again (specifically the living realm Amorta), starting from the second age, before sentient life came to be. The Astrone (and some spirits/non-Astrone) from what-was-the-past remain, along with their knowledge of the old world.

This would be more likely to happen if her creations began to pollute the world (yes, similar to what's going on with earth), overpopulate, or if the world itself began to die. Except, there would most likely be times (to Nephi's plan or not) when such events could occur and play out, which could give rise to a new age, with new creations or evolutions. When the Astrone begin to weaken till they are no longer active (e.g. when the Earth Astrone loses her power from nature, or the Air Astrone is weakened by pollution) is when Nephi will be more likely to act upon this time reset.

A final note is that technology, powered by electricity, is a forbidden rule on Nephi's world. While it is possible that such devices could be created in future ages (perhaps something to do with the Lightning Astrone or even my minor Astrone of energy and stamina Drein rose to power), such devices are meant to fail, (I wouldn't mind one day exploring a weird magic-lightning system of electricity for a new age).

Wait... gods CAN die?

As explained, gods can die by using up all their power or battling another god, alongside the destruction of the universe.

"Only a god can kill another god" ~ Ares (Wonder Woman 2017)

There is no other way that a god can die, but perhaps the death of a god could have some advantages. For one, perhaps the defeater could absorb what power remains of the other. Or maybe, under the perfect circumstances, the death of a god could lead to the creation of a new one, their remaining energy scattering out into the universe where it could take on new forms within nurseries.

Just an idea though, and most likely will be discarded.

If Goddess is the name for a female god, and Nephi is referred to as female, do gods actually have a (physical)gender, does that mean gods could reproduce?

If gods could reproduce, it's not how you think, they don't you-know (don't you dare start💀) at least they don't do that when they plan to have miniatures, (gods are technically advanced shapeshifters, they could live like a mortal if they chose to, or they could live like Nephi - all gods are different, with intentions, personalities, or even none - in an alternative universe, the Astrone would be real gods cooperating on a world).

Taking minor inspiration from the fact that many godly mythologies on Earth have family trees, there probably are divine families in the myth universe and it involves some sort of power transfusion between the godly parents. It would differ from how a goddess like Nephi created her divine (non-god) beings the Astrone.

Perhaps a lot of time is needed, or maybe they have to travel to locations where gods are born.

This is something I haven't decided on (obviously). The idea of a family tree of gods for some settings is interesting, but based on the lore of how gods are born, it doesn't make as much sense.

While the power of gods can grow over time (which can come from advancing their power, practising, creations, time, etc.), how do they have enough power to join with another to create something just like them (and then again!)? It would weaken them significantly to create anything near powerful enough to embark on a godly quest of occupation.

But wait! What if... what if they aren't meant to be strong? What if these god families act more like the deities mentioned on earth, with each descendent representing and gaining their power from elements/principles/etc.? Each new generation could become weaker and weaker in power so they soon are just representatives of their connected 'element'. This is very similar to Nephi's Astrone. They will never be able to leave their world, and could probably be considered as something other than a true god (maybe this is like the Titans to the Olympian gods - damn I need to research more on mythologies :p)

Well... looks like that's that for now...

Any questions, please feel free to ask, and I'll go into plotting mode to find the right answer.

For something that isn't entirely needed in myth's lore, I sure did write way too much. I might right about the basics behind the astrone next, however... they are underdeveloped, and I have to warn you that there is a disturbing story lying in the lore behind Radein (lightning and power), Xorvceious (malevolence), and "Poldra-who-needs-renaming"(tyranny and also power - not referring to strength which lightning holds)

Further warning: All of my ocs are fcked up (typical trauma I guess - more like sad/cruel stories, bad endings), which is why I say Nephivia is a cold and apathetic ruler (but I'm to blame aren't I? Cause not all are in the myth universe *cry*)