I always liked how the titular character's description contrasts with the melody. while Ozzy sings "He turns tears into joy / Everyone's happy when the wizard walks by", the rest of the band pretty much invents heavy metal in the background. I tried to capture this ambiguity by drawing him in this friendly stance with arms open, while also riding a giant menacing bat. I also tried to create a bit of contrast in the styles of the character and the bat

I started with a very loose sketch, trying to solve the compostition and convey the mood I had in mind. Then I proceeded to cleaning it up, defining the bat's anatomy better and detailing the wizard.