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Super Peach Castle is a portion of Peach's Castle in the game Mario & Luigi: Bowser's Inside Story. Bowser must become giant to fight it. When Bowser follows the incomplete Dark Bowser out into the castle grounds, Dark Fawful arrives in front of Bowser, who gets annoyed. Dark Fawful then mentions how he needs more power. He also replies that Bowser's meddling has given him fury as large as the world, then taunts Bowser while saying "SUPER PEACH'S CASTLE OF FURY!". This commands the castle to transform into a giant Mecha, crushing Bowser. Afterwards Mario, Luigi and Starlow go to the Rump Command and make Bowser giant again. He then fights the castle.
Super Peach Castle starts off the battle by creating a black hole that forms behind Bowser, making it so that Bowser must beat the vacuuming force of the black hole every turn (or at least until phase 2 of the battle starts). Shortly into the fight it deploys a horde of Mechawfuls, requiring fire. The Castle reacts to the flames by "ejecting all heated cargo," giving Bowser a Refreshroom. After Bowser deals enough damage to the castle, phase 2 begins. The castle will fire an unavoidable laser beam, which will instantly suck Bowser into a black hole, so the player must stroke right to get out of the black hole, and launch himself towards Super Peach's castle, dealing damage. The Super Peach's Castle tries to make a second black hole, but Bowser shoots a fireball at it, making the black hole go behind the castle instead. It will then put up a force field, preventing damage from Bowser's attacks, so he must try to launch Super Peach's Castle towards its black hole, then it will launch it self towards Bowser. He must punch to deal more damage to the Castle in this phase After a while, the Castle will make the black holes come closer to the two titans, making it all the more harder for Bowser to attack. If the Castle is sucked into the black hole in this phase, it will activate the Boo Shield, making it invisible as it launches itself toward Bowser, so he must time his punch to avoid damage. Near the end of the fight both Bowser and Super Peach's Castle will be sucked into the Black Holes and Bowser must keep launching himself towards the Castle, but it will release spikes from its hands, damaging Bowser if he launches himself, but it retracts a little after, so he must time his launching, or he will take damage from the spikes. After a long and hard battle, Bowser successfully demolishes the castle, and moves on to defeat Dark Fawful and Dark Bowser.