Sarasaland Adventure v4.0 (SMBX) - Acidic Ascension (8-7; Koopaburg Special Level)
Info: https://rpgmaker.net/games/4216/
If you've played DKC2, think 'Toxic Tower', only much harder. That's what this level is all about. The final three stars of the game (if you've already got the others) reside in here, and you'll be flying inside a Lakitu's Boot attempting to outrun the rising acid, while avoiding the many obstacles and enemies on the way up. It's rather short, but this is also one of the hardest levels in the game because there is LITERALLY no room for error (as you can see by my first death) - if you get hit by ANYTHING on the way up, you'll lose your Lakitu's Boot, and the only thing you can do then is wait for the acid to come and kill you, forcing you to start over. And there are no checkpoints, so you also have to do it in one go.
This is also the only level in the game that has Hammer Suits for power-ups, which is good because they definetly help in disposing of enemies on the way up. There are also coins placed to show you where to go, as well. You'll want to be quick mostly, but once you get to the rows of spikes where koopa shells are being kicked at you, you'll want to slow it down just a bit so you don't get nailed by them.
This is probably the level that will eat up a lot of lives, for sure.