How do you defeat her, like seriously she takes no damage

I've been using a combination of Item Hunters shield to block all of her damage and the 'Mean Marshine' scroll (though from what I've seen any weapon that does water damage is effective, there's a list here: http://www.subeta.net/forums/view/559707).

I defeated her with Classic Hero Sword & the Dark-Jeweled Sword then used the Mean Marshine scroll

I just keep using the plunger of doom, seriously it's cheap and very effective, she goes out in two hits ;D

OMG! Thank you so much :]

Water Charm and Item Hunters Staff works for me. I get her with just a couple hits. It's amazing. :3 Good luck! Let me know if it works for you.

thanks for the info!