Antasma

Antasma is the (supposed) primary antagonist in the upcoming game Mario & Luigi: Dream Team. He is some sort of king who destroyed the Darkstone in order to create chunks to freeze the Pi'llows. It's not yet known why he did this. Mario and Luigi are tasked with rescuing the Pi'illows which Antasma froze, as well as Peach (who he abducts early in the game). Little is known about Anastama's abilities at this moment, but it appears that Antasma can turn into a bat, not unlike what Cackletta's clones can do; on other occasions he is seen as a cloud-like being, notably while he is carrying Peach. He can seemingly also possess beings, as both videos and pictures of the game show Bowser as coming under the possession of the fiend while trying to kidnap Peach and subsequentially being used to attack the brothers; while possessed, Bowser gains a purple aura somewhat similar to Shrowser's distorted coloration, and Anastama surrounds Bowser in a large swarm of purple bats similar to himself during the battle. In all his forms, Anastama seems to be able to create powerful sonar beams which are both ear-splitting and can destroy terrain.

Trivia

 * Antasma seems to bear similarities in appearance to all of the previous antagonists in the Mario and Luigi series. (Cackletta, Elder Princess Shroob, the Dark Star and Dark Fawful.)
 * Antasma's name is likely derived from the word "phantasma", meaning "spectre" or "ghost".
 * Antasma is the second (first being Cackletta) antagonist that possesses Bowser and uses him to attack the brothers before the final boss battle.