Here's some material for you. According to the D+D 3rd edition monster manual, Mephits are elemental creatures that "leak" into the material plane where it converges with the elemental and para-elemental planes. From this material, we can the surmise the relative positions of the EPs and PEPs by understanding that all such planes touch in some way, and adding in some good old fashioned hermetic magical theory, we come up several elemental "portfolios" that would read something like this:
FIRE and its attributes
Red, warm and dry, midday, purification through destruction, chaos, anger, renewal, the spear and sword, war, south compass point, the summer solstice, citrus fruit, palm trees, candles.
As you can see, this "portfolo" includes information that may not be useful to your game mechanics, but could be useful to the immersion storytelling you seem to be after. i can provide more material if you so desire.
Anyway, if all the planes touch, then where fire meets air is smoke; where it meets earth is magma; where it meets water is steam; so forth and so on untill all options are exhausted.
This will indeed be hard to use for the system itself, but I see the potential of it if used in the development of the elements; story-wise. The portfolio's from water, earth and wind would be awesome to have.
I haven't worked on this project for a day, I can't always find the time. Yet, the day before yesterday was something I enjoyed very much. I started with writing out the system for Little Sin, starting with what the statistics are and how they work. Because I'm a little to lazy to summarize it, I'll post it here.
How the Statistics Work
The system will be based on two important statistics. The wisdom level (WL), which raises itself as you learn and study; supplies the mana and decides the base power of your attacks. Let´s say you use the passive move Ignis Gradus (Fire Step, we'll name it IG for now) this will take .. mana each second. Depending on the level of this ability, the mana drain can change. Dashing will double the mana use, making it .. mana taken from your reserves each second. Learning gives you strength and tools to use in battle. To use these in a correct way is a total different thing, experience is needed.
This is where the second statistic comes into play; battle experience (BE for short). As the player battles with magic and beat monsters/wizards, they gain levels in BE. With a high BE, you'll do more damage in battle situations. Still, this is not enough. To make this part more realistic and a little deeper, BE is broken up into a couple sub-statistics.
FmBE -> Fire Magic Battle Experience
WmBE -> Water Magic Battle Experience
AmBE -> Air Magic Battle Experience
EmBE -> Earth Magic Battle Experience
Every succesful hit and/or kill using a certain type of element will raise the experience of the BE linked to that element. I've been using Fire Magic as example until now so I will keep it that way. The more experience the player has in FmBE, the more damage he will do with this element. In order for me to even obtain IG, I need enough FmBE. (Level 4 is required.) So to get this, I need to train my FmBE up by battling using the most basic Fire Spell; Fire Ball. More on Spells later. Once the player gets strong and wise enough, they can obtain a second element. This can be any of the remaining 3, but I'll take Earth for example. Now things will become interesting. Once you reach a certain WL and find some important scrolls and/or books, you'll be able to combine both elements. The power of this third and final element in your characters life will be the strongest. Fire and Earth make Lava and the element isn't the only thing combining. The damage of this element is decided with the following.
FmBE + EmBE = LmBE (Lava Magic Battle Experience)
Because of this, it can be said that its highest level is 198. Unfortunately, combining two elements takes a lot of mana and while a Fire Ball is cheap if not charges; a lava bullet will cost something like a fully charged Fire Ball x 4. Reason for this is that all weaknesses have gone away. Not only that, the attacks are lethal.
Wisdom Level
Because the whole game is based around magic and the life as a wizard, spells are very important. However, not every spell can be used nor obtained without the right amount of knowledge. To make this possible, WL is brought in once again. It is needed for the battle system to work, but it was also brought in to make the game-play a little more interesting for the player. The most basic forms of magic can be learned without any of it and the teacher will bestow a little wisdom as the player does. So, how to raise something important like this? Without mana, a wizard can't be wizardly.
Throughout the game, the player will have the option to read books. Some are about culture, some are about stupid jokes and some tell the player about legendary figures and myths. The latter is of importance to the player, as these will reveal the locations of powerful magic and objects. Every time the player reads a book, they gain experience. The amount is decided by the difficulty, origin and content. It's very simple really, as you can see.
That's it for now. I'm going to my girl in for the coming two days, so I won't be able to work on anything besides this and maybe some characters if I'm up to it. Feedback is always welcome
YellowPepper