[Astral Harmony]

@ Secretskull: Nope! Enhancement magic does all elements in a variety of ways from offensive to defensive to terrain effects.

For example, one enhancement and fire spell is Burning Skin, which sets your body ablaze and harms (and ignites) any foe that attacks you with melee. In that same right, it's only logical that you can set a tree on fire by touching it with your Burning Skin.

As far as magical mastery goes, let's take it into the battlefield. Suppose you have fire elemental magic and you're faced with an ice-elemental Spiralis. The Fire Bolt (basic mastery) spell does good damage. The Magma Flare (expert mastery) spell does damage that a weak li'l Spiralis can in no way stand up to. But a guy with only basic mastery of fire won't even have access to Magma Flare, even if he has the mental capacity to learn and wield it.

The Control Field element is all about negative status effects, whether they are generated by elements or something else entirely. Specifically, Control deals with hampering enemy performance, like locking them in place or reducing categorical defenses (like a ghost's spectral nature), denying all logic and physics.

Magic in this system is going to be like a spider web. One might find that the spells of one element are actually the same as spells coming from many of the other elements on top of spells unique to itself.