The Wickedest Witch (1989)

Avarissa is a witch so evil she has been banished to the underground kingdom of the Greevils. She discovers in order to be freed she must convince a human, pure of heart, to commit 1 despicable deed.She sends a Greevil named Sammy to the surface to bring back an acceptable human, a child in fact. Once he's there she creates a 'Game Show" like enviroment to convince the kid to do an evil deed.