Zhered-Na was one of the most powerful magic users of her era. She possessed vast precognitive abilities and could access the astral plane as well as other dimensions. She has also proven able to transport others across dimensional barriers, project magical bolts, and magically extend the lifespan of a disciple by over 20,000 years.
She has sometimes invoked such entities as Valka and Agamotto in her spell casting.
She possessed a book which held all of her magical scrolls which has since been called the Tome of Zhered-Na. It is supposedly one of the most powerful books of magic ever created, though its power is presumably less than that of the Darkhold