It happened so suddenly, and quietly, but it happened all the same: the hardworking students who had been studying at the Slytherin study tables suddenly found themselves pushed out of their seats, shoved out from their desks, rolled out of their common room, and generally ejected from their House's private area.

An unseen force repelled all Slytherin students from the Common Room and attached areas, and locked all entrances and exits to the rooms. The Common Room was officially locked and sealed.