Because I can!!!

Intersection 1

First intersection of the stage.

Four paths forward.

Two doors below on the left.

One door below on the right. You can go through the top door here, that is. The bottom door will only open leftward.

If you take the bottom door on the left, you end up at the bottom door on the right, plus one invincibility.

A path on top to the right.

But both paths that go to the right lead to the same place.

Intersection 2

From intersection 1, take the upper door on the left.

Two paths downward. There's also an "illusion wall" with a hidden path leftward.

The hidden path leads over here. You'll get extra bolts this way, but you'll also face more danger (maces and lava).

The hidden path and the leftmost path downward both lead here. That upper door in this screenshot is from the left path down; if you take the hidden path, you'll enter this point from the left. You can just about get the invincibility without going through that bottom door. The bridge gives way when you step on it.

The right path downward leads here, intersection 9. Over to the left is a dead end because of the one-way door from the above screenshot.

Intersection 3

From intersection 2, take one of the leftward paths. Or, from intersection 9, go right and take the warp zone.

You can go right through the door to intersection 9 or down through the bridge to intersection 4.

Intersection 4

You'll go right a ways past some lava and slope challenges. You can go up or right.

Going right will eventually lead you to this dead end. Going up will take you to the other side of this door. In this way, if you go up and through this door, you'll loop back around and get back to the spring in the above screenshot.

Intersection 5

From intersection 4, go up.

Going right here will loop you back to intersection 4. Going up will lead to intersection 6.

Intersection 6

From intersection 5, go up.

From here, you can go right or left.

To the right is a dead end.

To the left is this thing. You can go up or to the right.

Intersection 7

From intersection 6, go left.

Like I said, you can go up or to the right here.

Going right will take you here. Drop down to loop back to the dead end to the right of intersection 4.

Going up leads to intersection 7.

Intersection 8

From intersection 7, go up.

There's two paths down. There's also a door on the left that goes back to intersection 6.

But the two paths down meet up like two seconds later.

And that path goes down here to the boss door.

Intersection 9

From intersection 2, take the right path downward. Or, from intersection 1, take the right path downward. If you go from intersection 1, you'll pass a lengthy sequence of enemy and lava challenges.

From here, you can go left or right.

Going left, you can pick up an invincibility. You'll hit a dead end, though. On the other side of that door is intersection 3.

Going right ends at intersection 10.

Intersection 10

From intersection 9, go right.

From here, you can go up or right.

Going up will lead you to intersection 9 via the rightward path from intersection 1.

And going right takes you to this warp zone...

...which plops you at intersection 3.