I don't know the exact wording yet but in the past such abilities interrupted the attack sequence, so ignore the damage after the wound that would have killed the bearer.
So if you had one wound left and someone causes 15 more, than you suffer that one, "die", come back on a 2+, with 1d6 wounds.
Stuff that profits the chances for a certain roll on the EotG:
- Slann Starmaster or Kroak near for the third dice on the engine
- Curse of Fates to get a +1
- Skink Starseer to get rerolls
- Kroak's command ability
For the math... sounds like a job for
@Canas , it is a bit too complex for me.