The Seventh Heart Pillar in Flopside
After returning from The Underwhere, Mario again possesses the newly filled Pure Heart. Next, find the Heart Pillar in the underground outskirts of Flopside.
If you have already paid Welderberg 300 coins for the direct connection, you use the blue warp pipe and get to Flopside without a detour.
Otherwise, you will have to travel through the Mirror Hall again. Go on level 1 of Flipside to the blown city wall, turn the hidden switch with Fleep and follow the path through the mirror portal.
After arriving in Flopside, enter level 2 near Nolrem’s house and the elevator to the Flopside Tower.
Switch there with Mario to the 3D view. In addition to the elevator or Nolrem’s house, you can see an open gate and a narrow path that leads out of the normal screen level.
Go through the gate and follow the hidden walkway. At the end you switch back to the 2D view and run to the left.
Jump into the green warp pipe.
Through the subterranean outskirts
In the next area you run completely to the right. Along the way, you will encounter some squigs and squogs. You can defeat them with Cudge or Bowser’s fire breath or bypass them laterally in the 3D view.
At the right end you reach a second green warp pipe. Climb in and get even deeper into the outskirts of Flopside.
Follow the path to the left. On the way, you can fight other opponents, but this is not necessary for the actual solution.
Shortly afterwards, a very high stone wall blocks your way. Mario, Princess Peach and Bowser cannot overcome this obstacle.
So switch to Luigi.
Hold down the direction button on the ground until Luigi has fully charged his jump. Then let go of the button and make his huge super jump.
With the Super Jump you can easily get over the wall. If you do not jump far enough to the left, get a little closer to the obstacle and try again.
The Revived Pure Heart
Just behind the high wall is the seventh Heart Pillar. You do not have to solve any more switches or puzzles this time.
Approach the Pillar and use the reinvigorated Pure Heart you got back from Queen Jaydes.
The Heart takes its place and opens a new violet world door on the Flipside Tower. It leads back to The Underwhere and thus to the seventh chapter.
Tippi also points out that only one Pure Heart is missing. The decisive confrontation with Count Bleck is thus getting ever closer.
For the way back you can jump over the high wall again and run back the entire way through the two tubes. It is much faster with the retreat tube from the menu of important objects.
Use them to return directly to Flipside Tower.
Before you start the next chapter, you should save your progress and pack some healing items. Luigi’s super jump will be needed several times on the upcoming journey to The Overthere.
Enter the new purple door. Chapter 7-1: The Underwhere.