Despite Karl's suspicions, Tiffani's group had registered completely legitimately. Matilda had informed the vampire that the arena would open, and she informed one of her friends to come watch the fights last night, then to register for the morning.
So, while four of the five had not been here, one had, and that was all you actually needed to register for the arena in advance.
They were no longer taking reservations for the following day, though. All battles registered today would expire after a day. If the line got too long, the fights would expire, and you would have to register again.
That should take some of the risk of fighters not arriving on time for their fights, due to long wait times.
But the number of them who had chosen to register in groups of five to fight a boss level monster would do even more. Five individual fights would take quite a while in the arena, but they could have twenty challengers on the floor to do four boss fights at the same time.
