I was able to find out what happens to the Trolls when you knock it down.

The game just gives him 100 physical damage resistance (prolly cold, acid and electric too). So if you have a potent fighter (I have one) you can kill a troll with a critical doing over 100 damage.

Have fun!

Acid Works too! At least on the trolls I've encountered so far! When they drop, I have my mage cast Melf's Acid Arrow on them...They die!

'nuff said!

For me troll shamans were a pain in the ass. I became used to warm up groups of enemies with an initial fireball. After having great general success with this tactic I specialized my sorcerer in fire spells.
I was a little surprised that the troll shamans usually casted "protection from fire" after my initial fireball ... :D Reason enough for me to learn Melf's acid arrow asap. However, everyone of my two primary frontliners now has an acid weapon at hand ... ;)

I actually like the fact that enemies try to save themselves! I think it's cool to see a cleric cast cure light wounds...Just before I waste them! Having troll shamans cast protection from fire is awesome!!! If I were a troll with any intelligence whatsoever - I'd by a few fire protection scrolls myself!

If I were a troll with any intelligence, I would just stay hidden in my cave and not mess with loud, smelly, obnoxious mercenary adventuring parties!! :lol:

Yeah! As far as I know, Trolls must be killed by either fire or acid. I got to know this from BG series... Maybe in IWD they specify fire only

Fire or acid will kill trolls. Those little bottles of fire potion were good to make a final kill on a troll. I'm also very fond of magic weapons that have bonus damage such as +1d6 fire damage or +1d6 acid damage. If you find any - keep them ! They are very useful.