Always be circle strafing. She cannot lead her shots. As long as you're always moving in a circle around her and attacking her you should be fine. Let me know if you need more tips.
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I understand. It's admittedly pretty hard right now. In upcoming builds, I'm going to add things like armor and magic accessories that you can buy in town that will make the fight much, much easier. As of right now I would say the carbine is the best weapon against her, or if your timing is good you can throw bombs at her which should damage her even if her shield is up.