"Makes sense," Garrus admits. "Alright, bypassing the Hall of Mirrors. For now."

They bypass the Hall of Mirrors, Deekin looking moderately disappointed.

The next obstacle they encounter: an ogre, backed by a handful of orcs.

"Death to da small folk!" he roars. "For da Boss!"

"Diamond Spray."

The orcs go down; the ogre, though gruesomely wounded, stays up and charging.

Then Deekin stabs him, and he goes down.

"Ooh, Deekin feel vital," Deekin says. "Love that for Deekin."

Belmarniss looks for funny looking sticks.

None on these fools. She finds a shiny chunk of topaz on the ogre.

Any of their swag magic?

Nope!

...There's some magic behind this slightly discolored bit of wall that's obviously, on reflection, a (nonmagical) secret door. Illusion and transmutation.

"Secret door over there. Illusion and transmutation. Who wants to help me drag one of these guys over to try opening it with their hands?"

Garrus volunteers!

The door opens without incident, revealing a room with a treasure chest inside! The chest is the source of the illusion and transmutation, or at least the subject of it.

Garrus taps his foot thoughtfully. "Hmm. Is 'behind a secret door' enough reason to trust a treasure chest in this place?"

"Not when we have this handy test corpse."

The corpse is induced to touch the treasure chest...

which turns into a flock of small bats. They scatter.

"Huh," Deekin says. "Not really trap, not really treasure. Weird."

"And too small to eat too. Somebody's just pointlessly showing off."

"Archmages be like that," Deekin nods.

They continue along the path, which twists in weird and unnecessary ways several times, and fight a couple more ogres and one troll, each of whom declares his allegiance to "Da Boss" and declares them "small folk" to be exterminated. There's not much challenge (or treasure) to be found, but at least it breaks up the monotony.

Eventually they come to a hallway-terminating door, behind which can be heard much ogreish carousing. "Deekin think this be room of Boss," Deekin whispers.

"Buffs for anybody before we barge in?"

"Do you mind if use the staff to cast Shield Other on you? I think you might be the most, er, fragile member of our party, and I'm the least."

"You will not catch me complaining." She hands over the staff.

And Jojo casts the spell and hands it back, and then they open the door.

It's a large room, with several mess tables and a few kegs of unknown provenance; there's a side door. The ogres (of whom none really stand out as a "boss") react to their intrusion predictably: they get up and charge. Jojo charges too, as Deekin begins singing and Garrus begins shooting, and general violence ensues.

Belmarniss has another diamond spray for the mob of them.

The ogres go down pretty quickly.

"Hmm. I imagine that door leads to this 'boss'... who no doubt heard us taking out his guards, and has had ample time to prepare. Deekin, can you Haste Garrus and myself?"

Deekin nods and starts casting.

Belmarniss tips over a table to hide behind and cast from.

Garrus does the same.

And Jojo opens the door.

The ogre who bursts out definitely looks like he could be "da boss".  His skin is a blueish lilac color, his tusks magnificent, and his skin wreathed in a curtain of flame. "Me crush you good!" he roars, before manifesting a Cone of Cold that crashes into the tabletops like a wave. Jojo leaps above the effect.

Deekin gets clipped by it, but doesn't seem to be very badly affected; he takes the opportunity to stab the ogre mage in the foot.