Hmm... I don't really figure limits are needed, unless someone tries to godmod or something.
And I suppose that, for the sake of this RP, I'll create a distinction between Magic and Mysticism.
Magic is formed by some sort of deal with an entity of power. Dragon, Demon, etc. This fact makes it inherently corrupting, though it is speculated that a powerful good soul could, in theory, bend the entity to their angle and use the power for good. Magic spells tend to be flashy, destructive, and fairly simple to cast.
Mysticism is a form of "Super-Natural" ability. Manipulation of Chi, Dim Mak pressure point strikes, and Ninjutsu techniques all fall into this category. In theory, any living being can access this power, however, it takes training, determination, and focus to do so. Techniques formed by this style tend to be much more varied, able to heal, stun, or any number of other effects, but either require time to manifest or precise strikes.