It's as powerful as the time you spend on it, the amount of energy you can generate for it, whether you are advanced enough to be able to use Runic vibration for it, how many days you have done it, and how consistently.
How much each helps, in exact numbers, is impossible to say.
As the jews curse all of us, of course protection can save from death spells!
I think limits are different for each of us, depending on personal power. I also see, the Gods will fill the gap (if any) to ensure each of us is protected by death spells and curses.
Misfortune can come from planets, internal hang-ups, and so on. So best protection against this I personally think is a powerful will, strong 3rd Chakra and Soul deep cleaning.
Yes, it saves from death spells, as well as from various misfortunes.
When I stopped doing the aura of protection for 3-5 days, I began to see people around me who had broken legs and arms in various locations, they had a cast on them, after what was shown to me, I resumed the aura of protection and since then I have been trying to do it every day.
You can also build defenses using runes in addition to the existing aura of protection.