In regard to the original post, if every villain is throwing a huge Death Curse at you, that's just not consistent with the books. A lot of dark wizards and creatures of the night don't think to cast a Death Curse because they're hugely arrogant bastards who don't honestly believe they'll lose or die. Think of Grevane when Ramirez opens up his throat -- instead of realizing he's about to die he just keeps trying to control the zombies.
Vampires, given their whole thing is cheating death, are going to be even moreso. Harry had a solid 30 seconds between actually beating Arianna in their duel and actually killing her, and she didn't fire off a Death Curse because she was in shock and disbelief.
Throwing out a Death Curse, to some extent, requires the humility and realization that you're going to die. The vast majority of supernatural creatures simply are not going to have that.
Yeah, I have to agree with this.