User blog comment:12shzarmai/Strongest Type Moon Entities/@comment-294304-20180718151503

I think last time Nasu was asked about it (he's asked about it a lot) it was stated to be Amaterasu, who is put as someone who only a serious Arcueid has a sliver of chance at beating. Remember, Nasu has stated multiple times that Arcueid is one of the strongest people in the Nasuverse.

Velbar, as in the whole thing, is stated to be a power on par with Amaterasu and even a single herald was enough to fell the old gods at the height of their power (including Amaterasu, strangely) so this puts it at a class far beyond Divine Spirits.

The correct answer, as stated by Nasu, is Kohaku in her Magical Amber persona.