[PvK]

I was mostly joking. I think it might work. It was reported in Dom 2 that tainted unit blood slaves could get sacrificed (and IIRC there was a way to crash Dom 2 doing that). I don't know about commander blood slaves or what happens in Dom 3 though. I also don't know if it would set off the amulet of vengeance or not (it might bypass that), nor do I know if two amulets of vengeance both explode - the second one was sort of an explanation point on the joke.

Phoenix Pyre, however, seems like another possibility. Though I think you're right that simple cold aura would do it, given enough time - you just need to keep the artificial battle going long enough, which is the other half of the "how to make this an efficient factory" question.