Mockingbird's scouts arrived by ship, a simple fishing boat. They were professionals and as such would not be easily detected by anyone. They would discreetly speak to the locals, easily adopting their accent and mingling with the population as if they'd been born there. It really wasn't particularly hard to get them to talk- recent events in the Land had been rather bloody and brutal, and such acts were impossible to keep a secret of for so long.
They would walk the shores, visit the pubs and taverns and even find work amongst the local fishermen. On stormy days when the sea was too violent to fish on they would follow the roads deeper to the interior of the country where the rumors would only grow in number and intensity. After talking with so many people it was only a matter of crossing information to see what checked out and what was an exaggeration. They also set up a neat network of civilian informers in order to know about who entered and left the country and by which means. The poor civilians of the Land of Demons were more than happy to accept a few coins for the simple exchange of information and Mockingbird's scouts were trained to a point where they could easily identify which civilians wouldn't double-cross them.
[Scouting the Land of Demons]
They would walk the shores, visit the pubs and taverns and even find work amongst the local fishermen. On stormy days when the sea was too violent to fish on they would follow the roads deeper to the interior of the country where the rumors would only grow in number and intensity. After talking with so many people it was only a matter of crossing information to see what checked out and what was an exaggeration. They also set up a neat network of civilian informers in order to know about who entered and left the country and by which means. The poor civilians of the Land of Demons were more than happy to accept a few coins for the simple exchange of information and Mockingbird's scouts were trained to a point where they could easily identify which civilians wouldn't double-cross them.
[Scouting the Land of Demons]