User blog comment:BlackWizardZeref/Theories on "God Slaying" Magic/@comment-24066070-20131101083700/@comment-24066070-20131101180114

Where was it stated that she learned it from a book given to her by Gran Doma? If this is true, then he should've learned some magic himself instead of getting his *** handed to him by Jackal.

All in all the author failed big time with this God Slayer magic and even Dragon Slayer and Devil Slayer magic.

It would've been much better if the author had split them all up, like Dragon/God/Devil magic and Slayer magic. Dragon/God/Devil magic would be what Natsu, Gajeel, Zancrow, etc use and is the magic learned from the legendary creature, a book or a crystal inserted into the body, while Slayer magic is the magic used by Zeref (which actually kills things, as one would expect from magic intended to slay).

When Zeref appeared after Zancrow was introduced I was convinced Zeref was using Wind God Slayer magic, since it was also black in colour, resembled wind and last but not least actually killed stuff. I assumed Zeref to be an actual God who therefore used God Magic, but that was never confirmed or denied (though it became clear he wasn't using Wind God Slayer magic)