The Avalon boss that's my newest Nemesis :]

HI everyone! OK, so I've been going through Avalon, taking some screen shots (hint hint), and I recently reached level 75, and Fianna Yellowknife gave me a quest for a new spell! :D The boss's name is Hrefna Nightfeather and I cannot seem to defeat her. I don't have any crowns so I can't use henchmen. I try everything I can think of. I can take out the henchmen, but she keeps killing me :(. So I am reaching out to you, my faithful bloggers, to give me advice on how to defeat her so I can turn my back on her forever! So far I think I lost 4 times. Please help me!!!!! :(