Welcome to the boards
I'm not sure exactly what you mean.
A 17 shift death curse would be a 17 shift attack? Is that how you're modelling it?
Typically, a death curse is enough shifts of damage that, given the highest defense roll of the target, they still take enough stress to fill all their consequences +1. (taking them out and allowing the attacker to dictate the take-out conditions - in this case, death...since it's a death curse)
So, with average endurance 3 stress boxes+mild+moderate+severe+extreme+1=24 shifts of damage. Then you assume they roll ++++ So a really effective death curse is about 28 shifts of damage. Although, I think a 17shift death curse would take out most NPC's since they probably don't use up all their consequences.
If so, a 16 shift block would negate the first 16 of 17 shifts and the target would only take one shift of stress. They would, therefore, survive the curse.
Also, you should have an option at the bottom of the thread to delete it, if you are the one who created it so you should be able to delete the redundant thread.