New Super Mario Bros./World 6-4

After several landscapes and environments, you've arrived at yet another barren cliff wall. Without any natural obstacles, Bowser Jr. has installed another classic Koopa Troop defense mechanism, the Firebar. With every bar strategically-placed on every narrow ledge and over gaps, a sharp sense of timing is necessary to avoid getting burned.

Level walkthrough
As you go right, you can see a large Firebar. They have been a staple obstacle since the original Super Mario Bros., but the geography of this level makes them especially hard to dodge. Carefully pass under the Firebar, then wall jump up the gap in the ceiling following the coins while still avoiding the bar. Jump up to the next ledge and hop into the air to grab the first Star Coin. Drop down to the right to continue onward.

Just like before, you have to tread on a narrow ledge, although you now have to contend with Firebars spinning in differing directions. Carefully inch past the first two, then take your time with the pair of Firebars after that. Move past them when you see an opening. Go on to the next thin ledge and move past two more Firebars, each of them too long to dodge by jumping. Once you make it past the narrow ledges, drop down. In front of you will be a gap, as well as two short Firebars. You can stand on the block the Firebars rotate from, and doing so lets you cross the gap easier.

Go up and right, dodging two more Firebars along the way, until you get to a red switch. Hit the switch, then run left and jump on the platforms formed. Wall jump to the ledge above. While evading the Firebar nearby, go right and wall jump between the wall to the right and the platform the Firebar is rotating from. On the platform with the Firebar, jump to the higher platform to the left, then jump over the gap to the left again to get the second Star Coin. Back on the previous platform, make a running leap to the right. You should trigger a checkpoint flag when you land. Go into the red pipe to proceed to the next area.

There are no Firebars here, but there are plenty of thin ledges. Since there is absolutely no obstacles except from the bottomless abyss below, you can take your time in this section. Fall down from the first thin ledge on to the platform, then walk to the narrow ledge on the right. Jump to the moving platform when it's at its lowest, as you can't jump as high as normal while on the ledge. Hop from the platform to the next ledge, then on to another moving platform. Ride the platform up to another ledge and jump to it. The ledges ahead will get shorter, but more numerous, as if forming a stairway.

Drop down the first three ledges, then jump on to the thin ledges heading up. Keep going up ledge by ledge until you can jump to solid ground, where you can see one pipe entrance and a junction of warp pipes. Go into the pipe to end up in a bonus area. Go onto the ledge and make your way to the right while avoiding the short Firebars below. At the right is the third Star Coin, which you can easily jump to. Jump to the lower level of ledges on the left, and this time scale the ledge while hanging from it to dodge all of the Firebars. Go through the yellow pipe, go left and enter the green pipe above. Go right to the flagpole to clear the stage.

Star Coins

 * 1) Wall jump up the gap after the first Firebar and keep hopping up to eventually reach the Star Coin.
 * 2) From the checkpoint flag, run and jump to the platforms to the left to collect the Star Coin on a ledge.
 * 3) When you get to a series of short narrow ledges, jump up as high as possible to reach a ledge with the junction of a warp pipe visible. Go into the entrance of the pipe there, then dodge the Firebars on the other side as you proceed to the right. At the end is the Star Coin.