A powerful enchanter, known only as the Witch, lived in the city of Borphee during the Great Monster Uprising, from where she taught adventurers new magical tricks to combat foes. Her prices (during the zorkmid inflation) were:

Contorto 44,000+1 when casting "Low Magic" spells
Visio 68,000+1 when casting "Middle Magic " spells
Incepto 85,000+1 when casting "High Magic" spells
Protecto 100,000+1 against "Low Magic" spells
+1 against "Middle Magic" spells
+1 against "High Magic" spells
Mojo 120,000+1 when casting "Low Magic" spells
+1 when casting "Middle Magic " spells
+1 when casting "High Magic" spells

On a certain Grues Day of this period, a powerful gremlin ousted the Witch from her home for a single day, where it instead taught new magical tricks in her place.

SOURCE(S): Legends of Zork