I don't know if this is supposed to happen or not, so I thought I would document it.  I was just scooting past a fell dragon and an obsidian golem, and next thing I know the fell dragon is flailing about like he's being attacked.  Then the Obsidian Golem dissappears.  I hovered over the Fell Dragon and yup, he's been quite damaged, and I'm guessing it wasn't the scouts standing nearby.

Here is the turn before the attack:

And after:

I know its a dog eat dog world, but shouldn't they be attacking Magnar's weak scouts that are just standing next to them?

I have the save game if required.