There's no such thing as a dumb question really
Maybe I should try harder, then.
You need to go to your quest-items, and speak the spell from Maxos (which you obtained in the battle tower I believe)
It will open up to you. Have fun!
I've done that: it removed the visible barrier, but now there's an invisible one that stops me getting close enough to the door to activate it. At this point I'm thinking it might be a bug...
For the record (in case anyone else bumps into the same thing) my installation is ED + FoV + yesterday's patch...
