Probably possible... but it would require real programming knowledge well beyond novice level.
So unless there's some magic box I haven't seen in the editor yet, consider it practically impossible.
As far as I'm concerned, I think the easiest solution would be the evented one as described above, where you store the current x coordinate in one variable, and an old x coordinate in another. You'll have a branch check if the current x coordinate is unequal to the old one, and if it is, you set the old x coordinate to the value of the current one, and do damage to the hero manually if he is afflicated with the condition (you'll need a branch for each hero for this).
You make an identical branch but with y coordinate variables instead to account for all 4 moveable directions.
This prevents the damage from happening unless you're moving, and if you don't want the damage to happen at each step taken, you can add another branch in there which checks if some counter variable has reached a certain value, at which point, you check if any of the heroes are afflicted with the condition and reset the counter variable.
This might sound complicated, but it really isn't all that bad.