If this has been posted before or is in some FAQ somewhere I apologize for asking, but it came up in a discussion with a co-worker today. What happens if a Fourtuned unit is the target of Null Zone (or Void or whatever the power is called for Space Marine Librarians)? One allows rerolls of failed invuln saves, one forces rerolls of successful ones. I think our mutual conclusion was that they cancel each other out, but I wanted to see if that was an overall accepted method of dealing with it.