I remember this from the demo, and TFL, but have not read anyone posting it.
Before you enter that final pass of Bagrada with the campfire that is lined with a few Soulless (the one where you get mobbed by the Trow and company); leave all of your troops except your archers behind this point. Let your archers through the pass one at a time, and lead them along the left wall of that huge area the Trow and soulless and thrall come from. Keep going clockwise with your archers, staying along the wall, until you start to see the Trow and un-dead army waiting for you. You can position your archers up high, just to the left of this army. Do not shoot at the soulless! (this will "wake up" the army), just keep attacking the ground so that you "accidentally" hit the thrall and Trow. After the Trow turns to stone, and the thrall are dead, you can target one soulless to kill it and then pick off the others. Now you can finish off the Trow and the level with a few more arrows and some hero archers.
