The Silver Star versus the White Princess of the True Ancestors.
Both at the peak of their power.
The fight takes place in Fuyuki City.
Starting distance of 500 meters.
Both parties will be in-character.
Only the basic idea of their capabilities will be given to each side (i.e. she knows Aleister is a magician and he knows that Arcueid is a nature spirit of some sort).
Win conditions: Death, incapacitation, or BFR.
nasu vs toaru is banned here