(Master Comics 016, 1941)
I always have an instinct to skip the really racist ones, but I think it’s better to acknowledge them? There’s lots of messed up shit in old (and new) comics, folks.
Anyway, Mumbo Jumbo is a guy named Graynor who poses as a voodoo god/ priest in classic (often quite racist) comics style and uses the believers at his command in order to… get revenge on his old boss. It’s a shocking lack of ambition on top of everything else – just as well that he gets murderated by Zoro the Mystery Man’s pet cheetah.