"Maybe the Ringmaster has a similar spell you can test it with." He puts a hand to his chin, thoughtful. "The ward probably means Nightshade can't find you like that even out of the carnival, but we should know for sure you'd know, right?"

It'd probably be a big help if Strange could know if someone was scrying for him--both for his personal safety and in case someone's looking for him to look for the carnival.