Where do I use this spell?

Hint 1 of 6:

Have you seen any creatures of the night?

Hint 2 of 6:

One even has the word "night" in its name.

Hint 3 of 6:

Night Mare -- the horse of the dead -- will work.

Hint 4 of 6:

She likes to feed on noxious plants.

Hint 5 of 6:

You must have seen one already.  In fact, someone even tried to get you to
eat it.

Hint 6 of 6:

How about the nightshade on top of the Logic Cliffs?