Troll Sabotage Quest/Spoiler

Required Equipment

 * Helmet of the Deep

Method
Find Jerom near Avar Tar.

Ask him about "Mission" and he will tell you that troll ruined him.

Go to the other side of the mountain and jump into the river, put on your helmet of the deep and swim under the mountain.

You should fall down a floor, swim to the water vortex and you are another floor down. Go out of the water and follow the way, you should fine the troll, however he's an NPC.

