This is level 11 of the Way Back.
(Note: Parts 8-16 of this tunnel can only be played with the Duplicator, so he will be the only recommended character.)
This level is fairly hard, because you are forced to use the Duplicator, and there are lots of Crumbling tiles. Usually, the Duplicator is avoided on levels with Crumbling tiles, because his duplicates can easily crumble them. However, on this level, you have no choice, so you need to avoid the Crumbling tiles as much as possible. Although the Crumbling tiles are in long chains, they are not all connected, so it doesn't matter if you break one or two sets.
However, this doesn't mean you can just kill the duplicates. If you had to clear a gap by jumping off duplicates, then this can be quite useful, as each player's special abilities have strengths and weaknesses. This level isn't that hard, but will still annoy some players.