Morgen,
I'm really tired today... Here is a Guide: How to farm ******* mountaintrolls.
Skills: look at the picture
Go to Droknar. Go out through the northernwest gate. Turn left and after a few seconds you can see a path into a cave. There are 2 heroes and it is plenty of mountaintrolls. Lure them around you and killem like the griffins. Have fun with that..
I had skilled 1 to axeskills, so it is very easy to farm them, even if you forgot to skill yourself right.
/edit: Make sure that you have enough mana to cast the leetskill, cyclone axe and energical spirit. At least one defense and cyclone axe. Energical spirit should be casted directly after the leetskill.