The term 'Mischievous Elf' can be summed up with the crossword solution of 'PIXIE'. A PIXIE is a mythical creature from European folklore, usually depicted as a small, mischievous humanoid with pointed ears and magical powers. They are often associated with fairies, sprites, and other supernatural beings. In modern culture, pixies are often portrayed as mischievous pranksters who enjoy playing tricks on humans.