From DDO wiki
While I understand that if something has as many negative levels as it has hit dice, it dies, I still fail to see how this is possible. See screenshot. 
- I've been neg leveled to death many times. I've neg leveled mobs to death. I've picked up 10 or 12 neg levels in one shot before, so it is possible that if you have 21-25 neg levels and get hit with a large neg level (5-12), that the coding could be bugged out and not kill you. Might be an epic vs. heroic bug. I'll research it more when I get time. ShoeMaker (Contributions • Message) 08:07, December 29, 2012 (EST)
- I have Divine Intervention on, which helps prevent dying. Even still, trying this again in a different quest resulted in dying after 29 negs and trying to get more. I'm not understanding how I got 33 without deaths, and a different time dying at 29. Let's just say that DI is a really weird thing.