Dark E.N.T.I.T.Y.

...E.N.T.I.T.Y... Is too strong... But with Dark Bloontonium and Dark Plasma, it becomes so powerful that nothing but dark plasma itself can beat it... Come forth... You have been powerful enough to destroy the Dark Plasma Boss before... This will be a thousand times harder... But you have dark plasma on your side... Go forth... Win... Or the world ends...

-The message upon reaching the Dark E.N.T.I.T.Y. chamber.