Antasma

Antasma is the supposed primary antagonist in the upcoming game Mario & Luigi: Dream Team. It is a being who destroyed the Darkstone in order to create chunks that froze the Pi'illows. It's not yet known why it did this. Mario and Luigi are tasked with rescuing the Pi'illows which Antasma froze. Its appearance gives the impression of it as a nightmare which the Pi'illows fear.

Trivia

 * Antasma seems to bear similarities in appearance to all of the previous final bosses in the Mario and Luigi series. (Cackletta, Elder Princess Shroob, and the Dark Star.)
 * Antasma's name is likely derived from the Greek word φάντασμα, (phantasma) meaning "phantom," "apparition," or "ghost."
 * Antasma can apparently turn into a bat, as shown by the cover for the game. This ability is similar to one of Cackletta's attacks.