Just wanted to post with some more info. (This is on Village of Shadows btw, not sure how other difficulties operate). She starts with 9000 hp, and will fly away after destroying the two pillars. You CAN damage her before she flies away, but she will reset to 7000 hp upon flying away (I also think she cant be killed at this point.). So you can do 2000 dmg and after that anything else is useless until she flies since the health will reset.