Question. I don't know if anyone already asked it, but...
Magical Potential is basically the potential to influence/change the world, translated into raw, magical power. Unless, of course, I fucked up and it's all Fanon that won't be implemented here.
Assuming it isn't, however, a fuck-up...
A MTG Mage would, according to this theory, have a much greated potential than practically any normal girl that doesn't have Bullshit Protagonist Shenanigans buffing her (Madoka).
Now, about Planeswalkers.
We are not one right now, but one of the most important characteristics of a Planeswalker is that they have virtually unlimited room for growth, and their capability to influence the world/universe/multiverse increases with their power, experience and age.
So, if Magical Potential is the potential to influence the world at this time and in the future, except translated into raw magic...
...what is the Magical Potential of a person/being that is ageless(potential to change things isn't limited by time/age/lifetime), will grow in power practically infinitely (potential to change things increases exponentially with time) and can travel to an infinite number of different worlds (potential to change things in many universes, rather than just one)?