You can resummon her and do the fight normally with either the above mentioned cantrip from a wizard (which does not always work) or alchemist fire.
I used alchemist fire and she revealed herself and the fight was pretty normal with her cloning herself, then turning into her prisoner and then getting invisible. I like to stealth into dangerous situations and position my party, so I probably will never just stomp into aunties cave.
It's a pretty challenging fight btw.
