From RWP Wiki
The Mega-Glowbo is in item in the Banjo-Kazooie series
The Mega-Glowbo is, as the name implies, a powerful, larger-than-normal Glowbo.
In the Games
In Banjo-Tooie, it is found inside a giant ice chest on the ice side of Hailfire Peaks. It is reached through Glitter Gulch Mine, inside Waterfall Cavern by using the Talon Torpedo to bust down a wall into an underwater passage leading to the ice chest. To open the ice chest, Tooie's Ice Key is needed; it is found in a Banjo-Kazooie Game Pak in a cave in Jinjo Village.
Once collected, it is brought to Humba Wumba's Wigwam in the Isle o' Hags Pine Grove. Once this is accomplished, jumping in Humba's pool will cause Kazooie to be transformed into a dragon. Dragon Kazooie has the ability to breathe fire by pressing the attack button while standing still and has unlimited Fire Eggs.