[@Archmage MC]
She isn't able to counter mages completely. Any mage of similar power to Darquesse could still defeat her, simply by overpowering her or negating her magical abilities. You forget most mages have the ability to negate magic weaker than themselves (yes, even in D&D).

Warriors in the ten-tonner or beyond range would be able to fight her with relative ease. She has no abilities that make physical combat useless, and someone like the Hulk would annihilate her with ease.

She does not function without magic, as her strength/speed are magic-dependant, as are all her abilities. Without magic, she has all of the powers of a normal human teenager.