Just to reiterate, it was also mentioned that there should be fodder for the griffons. So that in the first round of battle, the griffons attack someone other than the vampires.

In the first round of the battle, the vampires will only face one stack of upgraded griffons. The vampires immediately take their place and are no longer afraid of anyone. Slowing them down is unnecessary :) Losing units as fodder for the griffons is not rational. If the vampires can survive in principle, there will be exactly 12 of them at the end of the battle. Otherwise, there will be zero. :) Mass slowing (as well as a curse) is practically impossible to have in the second week...