The Drunken Lizard Pub

So I'm in Omentors Temple, applied three of the artifacts to their machines - but the last one, that needs the bolt, is locked behind a gate, and I see no way to access it. What am I missing?

Go west and south until you find a lever near a pool of lava. The gate's lever is on the far side.

Ah! Thanks for the quick help. I had already been there, but assumed the pool is only a big trap...

(Ockham should have told me that it must be exactly this lever....)

Oh - it most certainly is a trap. A necessary one though.

That's why mages are so awesome.

[+] SPOILER

Fireballing the torch sconce so it triggers the lever and sets off the trap without you on it.