My problem here is: How can i beat "balor" The fire elemental guardian? He is very hard to be hitted and always attack me with a "fear" spell to destroy my party .
1) You really need to be 10th lvl.
2) If you have a Cleric, cast a curse spell on Balor. If it gets past his 20 spell resistance then his fear spell will most likely not stick.
3) If you have magic users blast him with magic missles while your fighters bean him in the head.
4) Make sure all fighters at least are boosted and fire protected.
I had the same problem the first two times I tried to face him.
I discovered that the remove fear spell is useless. So I cursed him and it worked! I play with a magic heavy group. A wizard, sorcerer, and a rogue with magic missle wand. Using metamagic both casters have magic missles in the 1st through 5th spell slots. They also have fireball spells for slots 3,4 and 5. Plus Ice Storm for slots 4 & 5. In Balors case I used nothing but missles.
I know this is late but maybe it will help others.