From Descent-Community Wiki 1.1
Play this card when a hero enters an empty space from an adjacent space. He tests . If he passes, he suffers 1 . If he fails, move the hero 3 spaces in a straight line in the same direction he last moved. For each space he cannot move, he suffers 1 or 1 (your choice).
Mage: If he fails, the hero is also Stunned.