In Fairy Tail, why couldn't Zeref just go to Edolas? Supposedly, the nature of Edolas prevents magic from being stored in the user's body or wielded. That means all Zeref needs to do to avoid killing everyone is to find a way to get to Edolas. 

Even if the immortality remains (which is unlikely in my opinion) the death aura is a form of uncontrollable black magic (http://fairytail.wikia.com/wiki/Ankhseram_Black_Magic)
First, I don't remind Zeref speaking about Edoras, he may have not been aware of it.

Second, in the comment section you quote the wiki : 


  "Ankhseram's "death field" is a magic spel"


But the line could have been written a long time ago when Zeref's demons and curses weren't a thing. Now in the tartaros arc we learn that the demons from the book of Zeref use curses which are not magic. Ankhseram's "death field" could also be a curse and then not be affected on Edoras.