Let's Go, Builder Mario!
From the Super Mario Wiki
Let's Go, Builder Mario! is a course which appears in the Story Mode of Super Mario Maker 2. It is Princess Peach's first job, which is unlocked after completing the main game. It is set in the underground theme and in the Super Mario 3D World style. Completing this course unlocks the Princess Peach Dress. This course teaches mechanics of the Super Hammer, which is also unlocked after beating the main game.
The course starts out with a Pipe which gives Mario a Super Hammer. He needs to power up into Builder Mario, then press to swing his hammer to clear away the Rock Blocks in front of him to clear a path. He can also hold down and press to create a Builder Box, which he can then toss to make a higher platform, allowing him to reach the next obstacle. A 10-Coin can be found nearby.
After this comes another pipe giving out Super Hammers, as wells as two horizontally moving Thwomps which Builder Mario can simply hit with a hammer to break. He can do the same with the two Big Thwomps which come next. After this is a Checkpoint Flag, followed by another pipe giving out Super Hammers and a path of Piranha Creepers which can be cleared away. There is one Piranha Creeper Builder Mario must put Builder Boxes on to get across safely. Two Horned Ant Troopers are up next, followed directly by the Goal Pole.
"Oh, Mario. The underground is filled with blocks, and no one can get through. But I'm sure you could clear the way with a Super Hammer. You need only create a Builder Box with ↑ and . Could you give that a try and see if you can reach the goal?"
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