Tsar Bomba

Tsar Bomba (also known as the floating bomb glitch) is a glitch that allows a bomb to be stalled in midair indefinitely during the Hariet fights in Bowser's Kingdom and Dark Side. The glitch is caused when Mario knocks both of Hariet's bombs back at her at around the same time; after the first bomb stuns her, the second will stall at the end of its trajectory and float indefinitely. The floating bomb can then later be used to stun Hariet or cancel her hovering attack even before she has released any bombs during that phase, which can speed up those cycles. The trick is generally used to speed up the second phase, saving around two seconds overall.

Execution

To execute this trick in Bowser's Kingdom in a speedrun:

• Upon starting the fight, immediately roll directly forward, then roll cancel down and to the right. This positions Mario in the correct spot while also ensuring Hariet does not perform any extra hops.
• Around when Hariet performs her fifth and final hop, throw Cappy again without touching the control stick and keep the X or Y button held to stall Cappy in place.
• While keeping Cappy in place, walk to the left a bit so that Mario is standing just behind where the left bomb will land.
• Just as the two bombs land, shake the controller to home Cappy in on the right bomb, sending it toward Hariet.
• A very brief moment after Cappy returns to Mario, use Cappy to hit the left bomb toward Hariet. It's best to perform a slight hop before this cap throw to allow Mario to immediately dive afterward and begin rolling toward Hariet.
• If done correctly, the bomb should hover and spin in midair indefinitely. As soon as Hariet emerges from her hat for the second phase of the fight, assuming the bomb was positioned correctly, it can simply be knocked into her to leave her vulnerable, essentially skipping the phase.