What was the supernatural doing in lesser known (or at least referenced) historical events, like the Polish Deluge, collapse of Carolingian Europe (and the root of the Carpenter line), the 30/80 years war, the 2nd Punic war...
But of course those aren't gonna happen because then the author would have to know them well enough to tweak them. But MW, Odin, Ferro, and the former Red King would've seen them all (in the Red King's case, for certain values of 'seen', no idea if the supernatural was already global).
For more likely cases:
- The ascendance of Mab
- The first Knights of the Cross after TWC died. We suspect they have been here before then given the Kusanagi connection, but how did that all go?
- The takedown of Abdul Alhazred