Tom had effectively sliced through all of Dumbledore's spy warding. Nina knew it, but the others seemed confused as to why their Lord had unfurled his magic out of nowhere. The two shared a look, and Nina stood with her wand out, re-warding their dormitory in a way that suited their needs. He'd add his own later that night, Nina's warding wasn't as impressive as his but it would do for the time being.