Shrooom! is the guardian of the fourth "Your Sanctuary" location in EarthBound, Rainy Circle. It is capable of mushroomizing its enemies, similar to other mushroom enemies in the game. It is first encountered by Jeff Andonuts while he is en route to Dr. Andonuts' lab, in order to rescue Paula and Ness, but cannot be fought until later in the game, as it is Ness' sanctuary. The battle itself is relatively easy, as long as the player is lucky enough not to suffer too much from the effects of the inevitable mushroomization.