User blog comment:B214/Volume 21 info & spoilers/@comment-82.199.201.247-20160218162357/@comment-104.7.80.176-20160218171533

Plus it has only been confirmed that from crom cruach is in the same class as the heavenly dragons. But since it it said that crom cruach, Azi dahaka, and apophis are on par with each other I guess it is possible for those two to be in heavenly dragon class.