Through the vortex, the group of students would find itself in the entrance chamber outside Cascade Hall, usually presided over by the portrait of Tavarius Mims, who had decided to make himself absent for the duration of the festivities. The students’ final destination was the after party, held in the gardens, just the other side of the main front doors. Unfortunately, the doors were locked, and no alohomora charm would open them.
Aside from the relatively low-budget decorations that were strewn around the rest of the school to help portray the haunted house vision, there was only one noticeable alteration to this part of the school: a small wooden table, which held upon in three large tubs. As the students approached this table, they would see upon it a single sheet of parchment which bore one simple instruction: retrieve the key to unlock the door.
Evidently, the key was contained within one of the tubs. However, each tub also contained one undesirable filling, sufficient so that a student would have to submerge his or her arm at least up to the elbow to retrieve an item from the bottom of the tub. These fillings were frogspawn, some unpleasantly congealed green gunge, and live black beetles. Only one tub contained the key, and there was no indication which tub this was. Furthermore, once the key had been retrieved and used to unlock the doors, it would magically return itself to one of the tubs, and not necessarily to the same container each time.
While the students deliberated which container to try first, and who of them was the unlucky delver, they would be watched unseen by a creature locked in a crate and hidden by an invisibility cloak. The pogrebin was an unpleasant creature, and would instill a feeling of hopelessness in those nearby, a feeling that would intensify until they made it out the entrance hall and out into the gardens, where a celebration would be waiting.