And, since I am in the snarking mood... game designers: invisible walls are CHEATING. Seriously. If you make the terrain in such a way that a player can get up it AND you have every intention of the character getting to the terrain beyond, then WHY THE @#$%^ PUT IN AN INVISIBLE WALL?! Either make the terrain itself impassable (it's not that hard when players can't really jump all that high) or just accept that the player MIGHT just cut a corner here and there. What's it going to save the player? 10 seconds? When you put in FAST TRAVEL?! What's 10 seconds here or there? Gah.
I really hate having to do a @#%%^ death spiral just to get to whatever freaking objective you decided to be 'cute' with.