Well, she has a variety of magical abilities, including summoning, transfiguration, elemental skills and energy blasts. Some spells simply require concentration, some involve saying words, and some involve complete rituals. She can also fly on a broom, and can't drown. Some magic users have certain special abilities, and Gwendolen's seems to be leeching magical powers from certain people and things to use herself.
I'd say strong enough to beat a wolf, maybe hold out a bit against a dragon