Minutes before, the headmaster of the academy, Earl, had been running through the corridor of the academy in search of the professor and his students. He left the battle with Oliver, Noah, and Klaus. And with the cracks he heard earlier, he assumed that the second prince was already inside the academy, and he could dispel the veil that was trapping them inside.
Now was the time to move! Since the veil was already lifted, he needed to move the students into a different safe place since he didn't know how long will their defense last.
On his way, the headmaster encountered many monsters. But since he knew their weakness, just between the head where a crystal was located, these monsters would self-destruct and burn themselves into ashes once it was damaged.