The scenario “A Tear for Ossir”

Damn, this map evoked a lot of emotions in me, and not the most pleasant ones. I cleared the Dungeon, visited all the obelisks in the correct sequence, then I approach the last one, the one near the entrance to the dungeon, next to the last enemy castle (Sylvan), and it says that I need to take 3 steps back... and what does that mean? I've already searched everywhere, but it's no use!