Spark/Guide and Soul
Spark and Soul are passive/active pairs, respectively. Both of these classes are ‘one who utilizes potential’. However, utilizing potential makes both of these titles insanely expansive to the point that they could do anything. Due to this, the Spark and Soul have explicit rules placed on them.
Sparks and Souls are classes that test and utilize latent thinking. Latent thinking is a problem solving technique in which you look at all the different potentials/interpretations of a problem in order to solve it. A classic test is ‘how many uses can you think of for a paperclip’. Geniuses in latent thinking are able to come up with 200+ uses for a paperclip because they ask questions like ‘could the paperclip be 200ft tall’ or ‘could the paperclip be made out of rubber or glass’. These are the types of questions Souls and Sparks must ask to utilize their potential.

Souls and Sparks each have 3 rules placed on them that players must work around and figure out the potential of. The first is their aspect- what they wish to do must use some core of the aspect. A Soul of Breath has to utilize air, wind, freedom, or movement while a Spark of Life has to utilize life, health, regeneration etc.

The 2nd rule separates Sparks and Souls as classes- Souls abilities cannot directly effect other people, not even yourself, and Spark abilities must directly effect other people. Souls can indirectly affect others or themselves with their ability

let’s say the Soul of Breath creates a small ball created out of many swirling razor like gusts of wind and then throws it at an imp to destroy it. The creation of the ball didn’t directly affect the imp, only how the ball was used.
The 3rd rule is the most binding

the very first time you use any ability of your aspect whatsoever, the core of what you did is the only thing you can do. Let’s say that ball of wind was the first thing a Soul of breath did- they would be limited to creating objects. Or, let’s say the Spark of Life used their power at first to create a flower that exerted an aura of healing. The Spark of Life can now only create objects that exert auras. This part is also the most tricky to figure out- it has to be the core. The part of the aspect used (in the previous examples, wind and healing) are not core parts of what they did. Nor would be objects created and things like that be core parts.

This is the fun part to figure out if you are creating a character with this class- what would a gust of wind be at it’s core? I’d say it’s core is ‘movement’. A Soul of Breath would be limited to moving things to do with wind, air, freedom, and, well, movement!
I know this class is a doozy. But the basic is the 3 rules.