Boggarts.

By the hundreds. No. By the thousands if one were able to take a proper head count.

Infiltrating any and all dark crevasses found in Hogwarts castle, the swarm had moved across the country shrouded the mist in a collective effort to conceal them within it. Humans, magical and not, all feared the unknown and en masse this had become their most efficient means of mobility.

Those few who had been struck by Riddikulus remained hidden in their metallic sanctuaries inside suits of armour or the drawers of some of the cabinets lining the corridor. But it would take much...MUCH...more than that to rid Hogwarts of this infestation. A tedious task ahead but with an end in sight, maybe.

As one wave retreated, another wave swooped in. Trying to appear even more menacing and intimidating in forms than the first.