User blog comment:IamJakuhoRaikoben/Chapter 449: Mavis & Zeref, Review./@comment-112.208.140.131-20150824070212/@comment-9595671-20150827234654

I agree, most of the death curses we've seen so far are instantaneous deaths, but I always wondered if there was a form of Death magic that kills over time.

After all instant death is somewhat like mercy to most, so dying slowly over time can be much worse, just like living in eternal pain like Zeref has for most of his life.