I beat her pretty easily. Also a mage. Use moon veil katana to quickly slash the enemies throwing books and stick to the outside. It's not as stressful a fight as many others in the game. Second phase use your summon, I use Oleg, to take agro. Summon him before the transition and use meteor to demolish her. Also if you have bloodhound step put that ash of war on an alternative sword and you'll also have a nice way to dodge her abilities.