Magic Window is a secret Special Attack in Mario & Luigi: Bowser's Inside Story.
Procedure[]
When using this special technique, Mario and Luigi jump into a window, which teleports them close to a random opponent. The windows will appear at different orientations depending on which enemy is the target. As Mario or Luigi jump out of the window, the player has to decide which button to press: 
for Mario, 
for Luigi, or press both of them. If the player fails a button press, the attack will end. This attack costs 18 SP to use.
In the 3DS version, bungling a stomp does not stop the attack from continuing, and after ten stomps (successful or botched), a finisher is added where six windows appear and their respective doors open, leading to the Bros. jumping out and stomping a single enemy. However, in the Cholesteroad, the original gameplay is used.
Obtainment[]
This attack is unlocked by defeating the optional Shroob boss. The shape of the window itself seems to be modeled after the Shroob Empire symbol used in Mario & Luigi: Partners in Time, where the Shroobs were major enemies.
