"Quite, I believe. Many warriors and mages have tried to brave their way through this tower, but ultimately they were stopped by the endless hordes." And not the infrastructure. But then again, the Endless Castle is magical. It could have simply repaired himself.

"What I cast did not have any effect on the infrastructure, if it helps." And he is capable of many, many spells...

As they enter the entrance hall, the doors remain open behind them. The staircase leading up to the second floor has no doors either, while a shining portal swirls on the floor to their left.

"We can return here. There is a network of portals throughout the floors."

[ And the music changes... ]