I finally made it to the deepest part of Fell Woods, now I cannot kill any of the three spirit lights, I have tried all weapons and spells at my disposal????

They keep killing my entire party no matter what weapon or spell I use?

Your weapons may need to be magical. They may need to be made of a certain type. I just know that I had no real trouble taking them out.

Hmmm well anytime one of the Will 'o wisps disappears take advantage to throw a quick heal spell. Try to concentrate on one, and when it disappears concentrate on a second then back to the first when it comes back. They arent vulnerable to many spells, try magic missile though. Anyway good luck

Are you damaging them at all? It seems I was hitting them just fine with two Maces +2, where one does fire and the other corrosive...all of it seemed to work. Don't remember if my missile weapons worked though.

if you have the time, really try to go back to the Battle Squares in the ice temple. It's fairly easy to beat them all (at least it was for me on "normal") and you can outfit at least 3 guys with +4 and above weapons, not to mention other serious goodies.

I beat them with +1 and +2 weapons. The trick is to focus all of your attacks on one of the creatures at a time and don't follow them when they teleport away from you, use that time to heal anyone who is seriously wounded. Another tactic that really helped me to beat that fight was to have my cleric and mage cast protection from electricity on all members of the party. The extra resistance it granted cut down on the damage I suffered quite a lot. Also, keep in mind that the Will 'O Wisps have good spell resistance, so just discharge all your magic missles into them and then have your mage pick away from afar with a missle weapon. My wizard had improved spell penetration and she still wasn't getting through those things' spell resistance more than 25% of the time.