[quote=@j8cob]
<Snipped quote by Raijinslayer>

I don't think Devil Slayer magic does extra damage so much as it one-shots them. In the canon Gray only had to hit demons once to beat them, regardless of how strong they were.

And Dragon Slayer magic also has insane boosts. Literally all magic doesn't even effect Dragons except for Dragon Slayer magic. Even Curses don't effect them. Going from zero to anything is pretty good considering Dragons are alleged to be the strongest things to ever exist.
[/quote]

When were dragons immune to everything? 

When was it stated Curses don't affect them?