Ok, so it looks like our rays can't actually hurt the thief, and the druid can only do 1 dmg if he rolls max dmg while the thief rolls min defense. So I suppose we might as well have them all just defend.
Looks like this is gonna be a long fight. On the one hand we currently are pretty well set to win it, in that we do more damage on average and heal for half of it. Otoh he might steal the vamp dagger, transferring those advantages to himself, to combine with his already higher health and defense, which will make him nearly unbeatable if he does. To make matters worse for Nele, while we have good defense and healing scrolls to give us a chance, our allies don't, so he very well might have killed all three of them by the time this is over, and there's little we can do about it. Oh, and while we froze it for the moment, soon the dusk will come back into play, giving him a 50% miss chance on top of his other advantages. We'll almost certainly want to use the plague scroll on him, since it gives us 2 damage a turn that bypasses defense, if I understand correctly. Our Firewater looks like another key item, though I'm not sure exactly what effect +5 attack has. Would it add more than 2 attack on average? Also, if we have our pets defend, they will have an effective 10 defense yes? What will that mean?
Use Firewater
Use Plague Scroll