Because of its ability to jump high, the Lizard is the best character for this achievement in case you fall so you can jump out. Otherwise very simple.
The Child is another recommended character for this achievement because his lightweight allows him to walk on crumbling tiles without them crumbling away, ultimately aiding the completion of this achievement.
- According to Player 03, the actual requirement is 60% of the level.
This is the only Infinite mode level-exclusive achievement so far to have a unique icon.