Bad Magic Bayou was a large and bleak swamp located near the Spiral Mountain from past where the entrance is a tree trunk with evil face which needed 14 Jiggies to open.
That swamp is completely toxic which cause injure, tires good to pass through, 6 sand islets, walkboards, forest with poisonous vapors and thunderstorm. A haunted manor in top, maybe was the home of Winkybunion family in past before of Gruntilda and her witches sisters built their own castles in adulthood.
This place is exploited by Banjo and Kazooie where pair accept the Gruntling Commander's challenge, going in risk locations, light the candels, active devices with Battery Eggs, defeat Klungo for 2nd time and find Jinjos to win all Jiggles.
Was here that Banjo receive the candel transformation by Mumbo Jumbo and Battery Eggs for 1st time.