Witch Mermaids? What the hell is this, Jefferson Starships?
In her magic show, Shiny Chariot does some transformations, briefly going through some forms including a mermaid, a bird-like form with wings instead of arms, and a centaur, although they are so quick you almost have to freeze frame to really see what is going on. (She isn't nude in the show though; her performance outfit stays on, although it changes shape to match the form she takes on.)