ToME: the Tales of Maj'Eyal

So I killed Golbug for the first time (huzzah me!). anywho, i see this portal in the room behind him, but nothing happens. I did a bit of digging here and found a reference to an orb or something? I've picked everything up on this level, but the portal doesn't seem to do anything. Am i missing something here, or is something not working as expected?

Check your inventory, particularly the plot items tab. You'll see the orb there. And then you use it. This probably could stand to have a little more ease of usage added to it (I'm going to post something in the ideas forum now).

Hmmm. Thanks. You're right. I've played most of the game not really needing to go to inventory to do/use anything (other than a potion from an alchemist quest or similar). to be honest it never really occurred to me to start looking now this late through play. An auto use might be nice, but actually, even just a bit of a clue in the quest journal would also help. Thanks for the help though, was kinda bugging me.