Three words: Infiltration. Station.
Invaded.
Any Legends player worth their Lums knows what I'm talking about. Throughout the level, you're forced to take out every enemy in each area before the next one opens up. An easy task, maybe even a fun one... if Dark Rayman wasn't chasing you around the whole time. One touch from that shadow kills you instantly and forces you to restart the whole thing. Combine all of that with the 40 second time limit for freeing all of the Teensies at the end, and you've got what is, for my money, easily the most difficult level in all of Rayman Legends. I can't count how many tries it took me to beat that for the first time, and I still die often when replaying it.
Oh, some may deny this claim! Some may say that the aforementioned Cloud of Darkness or the Invaded counterparts of The Amazing Maze or Hell Breaks Loose are more challenging and rage-inducing than the station. But at least to me, those three are easier to memorize, especially so with the game's somewhat-underwhelming final boss, making them less difficult on replays.
With this level, you can have it as memorized as you want; if you miss
one attack, fail to bubblize
one enemy in the room and break the flow of the combat, either Dark Rayman will kill you or you won't have enough time to save all three Teensies, forcing a restart for completionists like myself. And if you're frantically trying to take out all enemies before your shadowy double can catch up with you, you'll probably miss an enemy, forcing you to go back and do it again. And again.
AND AGAIN! 
So yeah, I really don't like Infiltration Station - Invaded. Enjoy the rest of your day!
