Don´t take off your Dwarven Ring if you are using one from your last battle. It is very probable that you are still drunk, also its best to ignore the ghouls she summons. Druid or Sorcerer: use Magic Shield, and get a little closer to The Dark Dancer to corner her where you will know her position even if she goes invisible, shoot Explosion when invisible and SD when visible. Knight: Stay diagonal right next to her in a corner, use Exori to make her visible and melee her. Paladin: Use Explosion to make her visible and shoot, may be a good idea to shoot Ethereal Spear since most of your mana will be drained anyway.