Cu Sith's Lair

How do I open the metal gate? I've killed Cu Sith, and explored his lair, but I've found no way of opening the metal gate.

There's a fake wall between two open gates in a hall which leads into the big room in the north.

Thanks, would've taken me a while!

I can't, for the life of me, figure out what to do in the final room. I've killed all the orcs, and looted everything else, but I haven't found any thing leading me to the next step.

I believe there's nothing important. Just pick a few items, earn some XP and that's it, so the next step is to leave

When I take the exit portal, that is the same one I used to enter, there are only two spaces I can stand on, one of them being the portal back to the lair.