User blog comment:Miskos3/Fairy Tail Chapter 391: Gray vs. Silver, Review/@comment-7418318-20140704072547/@comment-25111584-20140704085211

Blocked by something? How? Dragons who can teach it have existed. The books have obviously existed. If somebody can still block learning Slayer Magic uptil now, it'd have to be something vastly powerful.

Slayer Magic has been overused, there's no denying the fact. God Slayers and Dragon Slayers keep popping up everywhere. But why the outburst about it being overused now, when we knew he was an Ice Devil Slayer quite some time ago... And I'd prefer taking down the number of Dragon Slayers or God Slayers, not the lone Devil Slayer we have. Plus, a Demon learning Ice Devil Slayer Curse sounds more plausible than some kid learning it from a book (I'm OK with somebody of Hades' level teaching it to Zancrow), and Orga ... not even a hint of where he got it from. Lacrima there too?