There is also a flag within the fortress, at its center. If anyone from the attacking party can break down the flagpole, it is also their automatic win, regardless of the outcome.
But there is one person who can break this balance, that is, obviously, the valkyrie; she is just too strong. If she fights proactively with all her prowess and abilities, it would be almost close to impossible to stop her.
So, by the collective decision of the professors, she would not be personally engaging in any notable positions in which she could use her battle prowess, so they would basically put her in the backseat.
While it does seem unfair for her, she is so strong that she cannot even engage in the competition properly. But for that reason, the academy actually prepared another small stage for her, something that would be held after this fortress game is over.
