Lost corridor in the Misty Woods
Ori and the Blind Forest GOOD EYE ( Lost Corridor ) Achievement Guide
The lost corridor can only be accessed after you restored the wind and collected the leaf that helps you float. Go to the left side of the big gap in the “Valley of the Wind”. This is the “Misty Wood” and you have to get to the very end here.
With the leaf and the newly restored wind you can get to the last section and collect the achievement.