Start with mimic summon and health flask (will have plenty of time unless this is the very first time entering battle area). Let mimic engage her first, and attack from medium distance with special. If you gain her attention look to guard and allow your mimic to regain aggro. Roughly every 4 special attacks should stagger her, but she recovers quickly. In phase 2 immediately dash under and past her to dodge her attack which will leave her in the kneel down (super hero landing lol) pose for a bit. I popped my flask of wonderous physic here (i have the tears for 10 secs no fp loss in that) and spam your special. You should be able to get her pretty low on health as she will likely be stunned coming out of her kneel pose. At this point its a race to burn her before she starts unleashing attacks and recovering health. Having your mimic at lv9 or max is a plus, as well as the Fallingstar beast jaw at max.