Okay so i have killed the will of wisps and Madae and her brother appeared etc....so I am supposed to follow the treants through fellwood to find the way out ??? My problem is they all attack me and if i go invisible they just stay there....Any help on what i am doing wrong would be greatly appreciated

No, the treants are bad. You have to waste them so they stop using their evil magics to confuse the trails.

When I first entered the wood, there was only 1 treant. Chased it to the next screen and there we were mobbed. It was a quite a fight; I had the most luck with swords, magic missiles and acid arrows. The path out of the wood then opens up right in front of you.

just fry those treants with a fireball or two...

What kind of damage does the Wisps take?

Any kind of physical - they just have high armor class.

Chop them down with your axes, then Fireball them, then beat the h*** out of them! HAHAHA!