I just beat her today. I was at like level 24 or 25 or something and each of the dwarves were like level 29.
when the dwarves started surrounding me after I entered her room, I casted invisibility or if you don't have that use a shadow potion I think.
Then when they couldn't see me, I would use the Warrior swirl attack and NOT target anyone which causes invisibility to NOT wear off. After that I used a teleporter stone to go back to Zandalor for some healing and renewed my mana.
And then I went back and became invisble again and used the swirl attack on Jospehine without targetting her while I was doing it and this caused her not to see me and when I almost ran out of mana I would refill it again and keep on doing it until she died.
Of course if your not playing warrior then please ignore this.
