Hogwarts is

You're on Scenario 1 of 7

Something is wrong at Hogwarts tonight.
The children are scarce, and full of fright!

There are ghouls and monsters, ghosts and bats,
evil dark witches with snakes in their hats.

A simple spell was cast on the grounds,
Now no one can see! This darkness surrounds!
With no one around and no professors to ask,
What spell do you use? What spell should you cast?

Riddles written by Allison Frederick & Kimmi Cranes