I have been working on the geodata today, looking how it was in Antharas's Nest and it seems to be ok. The problem is when you drag him to a wall, he seems to be elevated, somehow he climbs the wall to the top and he doesn't disapear but he goes to the roof, we are looking forward to fix this, for now you can try to kill him not so close to the wall.
Tomorrow I'll be looking at the geodata again and I will try something, but the geodata seems to apear in the floor, in this case Antharas's is not in the floor, he's elevated and well, somehow he goes too far up that you cannot hit him anymore.