A question!
Petrify! I think there's two counters - Glamour and Luck. How does Blood Vengeance work with it? Can it paralyze / kill me? I know Doctor Vastness has high mr, so I'm only hoping to Paralyze him. That's when the Tengus Onis Double Headed Snake of Death Chaff kills him.
AFAIK, spells that inflict death actually just hit for 999 AN damage. So if you managed to penetrate its MR with Petrify, your caster would get a MR roll versus Blood Vengeance. If he fails, he gets hit by 999 damage, otherwise the Vastness does.
If Petrify does not penetrate the Vastness's MR(likely) it will be paralyzed and I don't think that kind of damage triggers Blood Vengeance. However, actually using chaff against a Vastness is a bad idea, because Blood Vengeance will trigger even when it's paralyzed, and most chaff does little damage and has low MR.
At least, that's how I think it works.