M-2 is the second level of the M-Tunnel of Run 3, which is branched off of Level 33 of the Main Tunnel.
This level should be more suitable for the Runner than the Skater. It is because she is much slower than the Skater and is easier to avoid the crumbling tiles. If you are able to avoid the crumbling tiles, this level is a lot easier.
While using the Runner, try to keep in midair for a longer time. When you land, try to land on normal tiles. If there aren't any normal tiles in front of you, try to look and land on the wall.