Remus snorted, hip checking Sirius, but not making a true attempt to dislodge his arm. "I'm afraid Sirius is right about the Unforgiveables. There aren't any spells to counter them, let alone block them or keep people from casting them. Could probably work up a modification to a silencing spell that would do the latter. But, that will take time." Although, it was an interesting concept that would give him and Sirius something to work on. It had been ages since they created any new spells together, even if it was just two of them instead of four now.
"Between our own studies and the training we've all had to some degree or another from Moody, we should have enough detection spells to at least identify whatever spells are still in place by type if not specifics. Main entrance is as good a starting point as any," he agreed with a nod. "Work our way out from there. Slowly and methodically. May take a while, but we probably shouldn't split up until we have a better idea of what's out there. I'm not sure how we'd set an alarm for newcomers' though. Where would we set it when we could have newcomers in any part of the castle? We might want to suggest to the others that people try to avoid being anywhere alone, always have someone as back up, just in case Voldemort or Greyback or one of those ilk are the next ones the castle returns to the world."