Last time i get to Auntie i didnt kill her minions before ...
When she dispelled the fireplace i was like "damn" ... and i start focusing on minions instead since i was thinking that damage to her would be wasted anyway.
To my surprise she staybed and keep fighting for 3 or 4 next rounds ... but then when i decided to start damaging her again she run ...
So my guess is that she simply stay longer now before runing out and you were simply too strong for her to handle.
