Mim's dragon form
Whenever Madam Mim falls into lava, she uses her dark powers to transform herself into a dragon not unlike how her sister from the villain league, Maleficent, does things during battles. unlike maleficent, mim's dragon form is clumsy, goofy, awkward, and can't fly due to it's grand weight and tiny wings. Merlin usually only has to become a chicken pox virus in order to beat her during final battles involving the rest of the Villain League.