Did the Vastness have any protection buffs cast on him?
I did some testing and log diving
. The way blood vengeance seems to work is:
1. The damage that penetrated the protection of the vengeful one is negated.
2. As retaliation the attacker is hit by a AN attack with damage equal to the negated damage. This attack is subject to DRN rolls like any ordinary attack. (Which is why you sometimes see the little blood cloud effect on the attackers but no damage. Blood vengeance was activated but the damage roll was less then 1.)
This severely reduces the usefulness of BV. Building a strategy around BV would require low protection, inviting heavy damage from anyone with decent MR.
There are many other interesting things to test but no more testing for me today