After collecting the Ring Piece in Elementary Evil, Agatha and Malak start chasing you. To get this achievement, you need to not go into any fake portals. There are fake portals in the running sequence, and if you go into one, Agatha teleports in front of you. There are also fake portals in the bossfight, but there's a glitch that allows you to completely skip this bossfight, and it involves teleporting onto the stage, and staying in the corner.
The bossfight glitch: