Could you send us a screen shot of where they get stuck? I know the first section that they start in is impossible to move in except when they start up moving towards the X. If you interrupt that movement before they are flung to the other X’s, it is very difficult to get out of that area.
I was able to use the black flag on the Paladin when she was facing Nalfar. Until you defeat the shaman’s holding the soldier’s and archers in their spells, they can’t move. Below is a link to some posts that may give you some more insights for this level.
