User blog comment:FairyRaven/Fairy Tail Chapter 329: Seven Dragons, Review and Commentary/@comment-4829046-20130430111358/@comment-4829046-20130430131858

I made a fanfic of the reverse. How Dragon slaying magic is super-effective on Dragons regardless of the mage's power but is useless on regular humans due to the fact the the magic only penetrates a Dragon's scale and flesh.