If he stays in a region and you move a Noble towards that region on murderous settings, he should be considered Attackers and hence attack the Noble.
We've tried that, with no success.
The full situation is that the noble from the peaceful realm crossed the border, so he's inside our regions. The nobles of my realm have moved into one of our regions, set to murderous, while he's been static in that same region. Another time, we've matched his movement from one of our regions to another of our regions, and all arrived in the same region at the same time after turn change (still with units set at murderous). We also tried spreading out so that we had someone in any region he could move into. Nothing happened in any case.
So it seems like we've tried every way to trigger a battle with no success. We haven't even seen a message saying that he's evaded a battle.
