User blog comment:IamJakuhoRaikoben/Chapter 328: Zodiac, Review./@comment-3407832-20130420002059/@comment-202.164.150.62-20130420180218

In Rave it is an attack that wiped out a city with ease. Mashima said it was the same attack. What was shown against Jura might had been a weaker version of it. But if it has the same potential as Rave, the it is the strongest spell in FT.

But there could be spells topping this in FT in the near future. But as of now, there is nothing other than Acnologia's roar.