Vacuum Shroom

The Vacuum Shroom is an item in Mario & Luigi: Bowser's Inside Story. Bowser, after his last defeat, finds a random shop-like area in the middle of the forest, run by Fawful. He gives it to Bowser, calling it a "Lucky Shroom," and claims that will give him the power to beat Mario. He then uses the Vacuum Shroom, which gives him the ability to inhale everything like a powerful vacuum (similar to Bowletta in Mario & Luigi: Superstar Saga or Kirby from the Kirby series). It is destroyed after Fawful is defeated. When objects are inhaled by Bowser because of it, they seem to shrink drastically. The mushroom also makes Bowser feel tired.

The Vacuum Shroom is similar to the Invincishroom of Mario & Luigi: Superstar Saga; Both are mushrooms which were touted to have positive effects which do not actually end up being bestowed when consumed by the player (though it can be argued that it DID give Bowser the power to "beat" Mario, as he managed to "consume" him with it).