Mika wants you to defeat the Angmarim Sorcerer who is attempting to train the Gauredain to corrupt Mammoths.
'This Angmarim sorcerer dares to try and corrupt our Norsu, using idiot Susi-väki as tools. I suggest you look to the east and slightly north, on the slopes of those peaks just there across the road. They are rarely visited by us, and so play host to many undesirable creatures and väki.
'Search the area near Norsu-leiri! You must find the sorcerer who is giving the Susi-väki these tainted and dark instructions, and defeat him!'
The Angmarim sorcerer may be found east and north of Mika's camp.
Search near Norsu-leiri for the Angmarim sorcerer who is teaching the Gauradan the vile rites to ensorcel mammoths.
Norsu-hauta is south and west of the sorcerer's camp.
You should return to Mika in Norsu-hauta and tell him of your victory.