Magmus was first introduced in the episode; Hot Rocks. Shown to be the gardian of the underground (Center of the Earth.) when SheZow is given the task to save the world due to a volcatic erruption occuring. Magmus is shown with a protective and rude state at first. Then shown with an easy-going, rocker state when it's revealed that Guy and Mazwere supposedly "in a band". With his help the two were able to save the world, and make it back for the "Battle of the Bands Contest" just in time- earning themselve the name "The Eruption".
Even though Magmus does not have that much of an appearance other than a large structure of orange, dried, molten rock, Magmus does take the height of a large cave. Shown to also appear taller than the Meg-Guitarstage.