Is it just me or---
When Zeref talk to Hades.
He said
Acnologia is something triggered.
When Hades is "sent to hell" ( Nice line from someone who just made an appearance
)
He said
Arcnologia comes.
Is this some kind of mistranslation ? But, R is far from C on the keyboard
Or Acnologia is some kind of events, while Arcnologia is something different.
It would make sense, especially if Arcnologia is the black dragon.