I think either Ribbon protect against it, or that it's success ratio is pretty low at high levels. I know when I fought Archaedemon I cast Reflect at him to prevent him from fully healing himself by casting Death. I think I got hit by 10 Death spells during that fight and I didn't die even once.
The death I mentioned earlier was from the cursed ring. If I was indeed undead, it should not have killed me, I think. I'll try using the cursed ring with a bone mail to make sure.
-edit-
Nope, the cursed ring kills you even if you use the bone mail.