Well, I found out this myself and not sure if it is posted already but here it is.
You can deploy turrets inside walls (including scenario walls/oRVR) and they set them to agressive, they can shoot out of the wall and cant be seen/killed by anyone.... (as you cant target them)
To do this walk up to the wall (hard up against it) and deploy your turret.
I thought it was handy and helpful when it comes to scenarios especially Mourkain Temple, and any scenarios where you need to capture the Bauble..
I have been using this for the last few weeks.