User blog comment:FairyRaven/Fairy Tail Chapter 427: Pitched Underground Battle, Review and Commentary/@comment-25152698-20150406211400/@comment-1359322-20150407005635

Well since the purpose of this arc is to revive FT, i don't think we'll get any meaningful villain yet. Maybe after this arc. I still hope that we can see the remains of Tartarus and Grimoire Heart.

As to Gray's strength, hmm only time can tell or should i say the next chapter.