I READ about this little gem in the classic The Comic-Book Book (1973, reprinted 1998) by Don Thompson and Dick Lupoff. Dick O'Donnell's essay "It's Magic" enthuses greatly about Mandrake The Magician's earliest newspaper adventures, written by Lee Falk and illustrated by Phil Davis. He discusses one of Mandrake's earliest adventures, 'The Hidden Kingdom of Murderers', which first ran in US newspapers from February 3 to May 26, 1935.
Dick discusses one sequence where the magician's large Nubian manservant Lothar is forced to wrestle "the champion of the murderers" above a flaming pit. Naturally, Lothar wins. And Mandrake saves the doomed wrestler from a fiery death by levitating him to safety.
Amazingly, I found this art sequence (albeit, the Italian translated version) at the excellent Mandrake The Magician blog.
And here it is. Enjoy.