Giant spider on Isterreng
 

I do have quite big difficulties to kill the giant spider on Isterreng, in cave of frozen tears, which seems to be the first "boss fight" in the game. Is it must to kill the spider, so I could proceed on the main quest?? Is the spider somehow guarding the dark portal, which I had to close to proceed in game..

What combo of units you think are the best for killing the spider?

Yes you have to kill the Spider to move on with the game...

Trolls work well because they can regenerate any damage the spider does to them... Use the trolls to attack the spider and the other units to deal with the summons...

Take hard hitting melee units such as vikings, berserkers, sea dogs, pirates, etc.

Ok, I actually killed the spider the very next try after opening this thread, even before I read any of your replies.. but thank you anyway

Found the trolls, and they really made the difference, like Belgarath said..