Imperial Quest Elements

Water conducts electricity.
Fire is quenched by water.
Earth is burned by fire.
Thunder is grounded by earth.

In gameplay terms, that means that you want to use lightning attacks on watery foes, water attacks on flaming monsters, fire attacks on earthen beasts, and earth attacks on air-type enemies. [1]

In addition, elemental effects affect your vulnerability to other elements. [2] If you have a fire blessing on you, you take extra damage from water attacks. If you have an air mage granting you haste, you might want to be careful that you don't get slammed by an earth attack. Since the RPG Maker AI is fairly primitive, it might not matter too much- but it's extra important for player characters, since they'll probably need to take advantage of these kinds of openings to make the most of their spells and abilities.

On the other hand, a fire blessing gives you resistance to earth attacks, so putting a quick fire shield on an ally is a good way to make sure they don't get ravaged by earth elementals.

In addition, there's a second "primal" wheel that's completely unconnected from the first- the cycle of light, darkness, and void.

Light banishes darkness.
Darkness fills the void.
The void consumes light.

These have the same effects, but within their own limited scope- if a monster has a magical void effect on them, they'll take extra damage from a darkness attack. Dark-type monsters take extra damage from light attacks.

It's very possible for monsters to have one elemental type and one primal type. Candice the witch, for example, is a void spellcaster who also dabbles in water magic.

Anyways, that's the basics. I haven't had much time to work on anything super interesting due to long work hours, but I'm doing my best. Watch this space!

[1] In this schema, earth is wood, dirt, stone, and it's all equally vulnerable to fire. Similarly, air is lightning, wind, and flying-type beasties. This means that you can use root-based attacks on flying creatures, which if this was a Pokemon game would be a big no-no but in this case, I simply don't care. Maybe it deals extra damage because the magical roots reach up super high and slam you down, or because air creatures are fragile and therefore vulnerable to being bashed by rocks- I don't care. Pokemon has too many types and abilities and interactions and it's a giant pain in the ass to keep track of it.

Similarly, I know that ice doesn't conduct electricity, but it doesn't matter. Keep it simple, silly.

[2] ;)

[3] This mostly matters in terms of what kinds of abilities they get- human beings (and human-type characters) are balanced both primally and elementally, and are equally vulnerable to all magical effects.