Elmekia is a spell mentioned only once in the entirety of HPMOR, used by an older Slytherin bully. Notably, it passes right through a Prismatic Shield. "'Elmekia!' shouted Lee and Parvati shouted 'Prismatis!' and the rainbow wall formed but the fiery blue blast passed right through it like it wasn't even there, the bolt missed Susan by inches..." It is unknown if it is the function of the spell itself to pass through barriers such as these or it was simply the strength of the spell that managed to pass through a Prismatic Shield as if it hadn't been there at all, though also notably it does not "smash" the shield like Stupefy or Lagann tend to. It appears to be a reference to the Elmekia Lance from the anime Slayers, resembling the projectile in application.