I will try to /loc on my encounters with this bugs, i have seem yetis in north cave in dreadlands do that but not so often(like 10% of the time), its like they peek into a hole and go underworld, right at the hall from entering the cave and from the biggest room point coming towards middle, are like weak spots.
And that kaesora just found today, i gave up pulling these. (
http://wiki.project1999.com/Kaesora ) at point 1 going in the room under that room and try to pull mobs up