Flamberge is one of the major bosses in Kirby Star Allies as one of the three mages. Her power of choice is the element of fire.
The first battle was pretty decent, had its own challenge but rather easy.
In the rematch Flamberge is much stronger and her magic is much more powerful.
She's not impossible to defeat, but the rematch was one of the more challenging ones in the game that I can remember.