World 6-Tower (New Super Mario Bros. 2)

Star Coins

 * Star Coin 1: The first star coin is in plain sight, but Mario or Luigi can't reach it unless they temporarily turn off the Rocket Engine that's blocking it.
 * Star Coin 2: The player must enter the door left of the Checkpoint Flag (And turn off the Rocket Engine). The door leads to a large room infested with Rocket Engines. The second star coin is at the very top of the room.
 * Star Coin 3: Just before Mario or Luigi fight the Renzors, There's a green pipe that's yet again blocked by a Rocket Engine. After deactivating it, the green pipe will lead the player to a room with circling rocket engines. The player must climb the rocket engines to find the third star coin.