Great Mothers + Booming Voice + Zealous Ambition

Don't know why I never thought of this before (never really needed it, but still), but it just occurred to me that the bonus turns after each enemy death can lead to the enemy never getting a turn so long as you can kill them with one mass assist. 

Since NightSisters have lots of healers and supports, ZA makes that easy. 

Anyway, not particularly revolutionary and others have surely thought of it before, but I tried it and it works perfectly. For no tank and/or no attacker feats it's a cheat code.