These small devilish creatures love to play tricks on mortals. Often their tricks tend toward the cruel side. In some stories mages were able to sometimes summon these creatures to do their bidding.

(folklore) fairies that are somewhat mischievous

one who is playfully mischievous

a magical creature; it was a tiny, mischievous creature that grew up to 8 inches high; they looked like pixies, but they were usually brown or black and could not fly; imps inhabited marshy areas and ate small insects (FB)

An imp is a mythological being similar to a fairy, frequently described in folklore and superstition.