@Lav:
Interesting. Where's that from?
@ others: I thought double-dipping *might* be an issue, but it's true that you can't use them both at once. I'd be less likely to allow Athletics for magic, but idk...

Tedronai: In my view, the elements already overlap. They can all attack, they can all come up with one or more blocks, and they can all do (most of) the same maneuvers.

If I wanted to add Off Balance or somesuch to a group of enemies, it could be with whipping winds or water/ice on the floor or shaking stones or spirits grasping at them from the Nevernever or anything else I could think of. It depends on the practitioner.

Harry freezes things with fire (pre Changes) because fire is his jam. Maybe you freeze things with water or gale force winds.

You could obscure an area with smoke, some sort of veil/illusion, mist, fog/condensed air or a magical sandstorm. Each of the elements has it's things it's associated with in Harry/Jim's experience, but another player/practitioner could approach them differently.

I recognize the concern that having more elements would dilute the effects associated with them, but you can already get most effects with two or more elements. Having 25 (and being able to get the same effects from five or six elements) doesn't seem like a game-breaking deal to me.

Again, this is not saying you should make your players do it. It was mostly brought up discussing how to make an elemental specialist who could advance like a Wizard. I can see players/characters who would enjoy this and players/characters who would have more fun with the  5-element system.

I think it's important to understand that your elements are just how you see the world. So if your Cloud Evocations include some of water and some of air and lightning and whatever else, that's fine. Or if your understanding of water includes order and cleansing instead of entropy. Every practitioner doesn't see every element the same way and won't use it the same way. So (in my view) many of them could be narrower or more broad in range depending on the array of effects the player could explain (and the practitioner could wrap his head around) using thatelement.

And I agree Tedronai, many of the elements I listed (off the top of my head during a lecture /shame) step on other elements' toes. And a practitioner who understood the elements through a gazillion element system and chose 3 closely related elements would likely have a narrower range than someone who chose very different elements. This would be an issue with such a system, but not much of a handicap (just fewer maneuver options) in play.

Still, I can see the attraction of choosing something like Water, Ice and Blood. You want to be a kickin' water-witch (or waterbender, lol)

In fact, I think it would probably be a good answer to my original question of how to make a specialist keep up with someone who has full-blown Evocation. (With 3 related elements, you can take multiple specializations without running into the column issue).

And yes, obviously this bit of business would not be for every player or every practitioner. If it's a mechanical limitation, I'd think it relatively mild, but crazy element systems could open up options for players who were into that sort of thing.

Great answers all. 100 likes for Uncle Iroh...

Sponsored magic (or some variant thereof) seems like a good route for a focused caster with some additional depths.

True. I guess if you wanted to allow it, you could always houserule that Channelers can take Refinement for specializations.

It just seems counterintuitive to me that someone with just Evocation will come out of the gate as a better fire (or whatever) mage than a focused practitioner while also having more options. Again, nothing that couldn't be fixed by houseruling.