Hold Portal.

"You backstabbing sons of AAARGH!"

He can't rush the enemy because his subordinate is in the way (the other one made it into the room with the wizards). He'd order his subordinate to rush the enemy, but something tells him this wouldn't work, on more than one level.

...

"Maybe you can kill me, but I'm taking one of you with me. You wanna risk that? Do you?!"

Lucette sings something deeply unflattering! Who would have thought that the half-silver-dragon song-sorceress would use tavern songs about cultists being stupid for her magic?

A stupid song won't kill him... but the arrows will, eventually. Also, who the abyss thought it was a good idea to give magic to the mongrels?!

"I'm not dying to a bunch of mutts! Charge! For Baphomet!" He does his best impression of a minotaur rush at Lucette (with his glaive, not his head), but the water doesn't let him get up to a really impressive speed.

In that case a very well-bred woman of impeccable pedigree can be the one to fatally stab him in the back!

The second cultist is dispatched soon afterwards.

The sounds coming through the door, of heavy objects dragged or dropped (in one case on someone's finger), hint at hasty barricading.

"...Wanna just prop some boulders on our side and leave them there for the moment?"

That's a bit hard, because there are a few steps leading up to the door and the upper step is as narrow as the rest! They'd need a really big pile to stop the men inside from shifting enough rocks to be able to climb out over the top in a few minutes.

"How long do we need it to stay blocked? Do we want to check the door we blocked already?"

"Well, right now it's blocked from their side; I mostly just want neither of 'they come at us from behind later,' or 'we wait here for ages for them to remove their blockade.'"

"I think anything we can build in minutes, they can dismantle in minutes after we're gone. And we don't want to spend hours building a barricade, even if there's something we could do that would take hours."

Anevia motions the others away from the door. "I can trap the door," she whispers. "It won't kill them - maybe one of them, if we're lucky - but it might frighten the rest into staying put. I suspect they're already scared enough not to follow us, but if they think we're going to come back they're likely to run for safety, if there's more of them somewhere in this maze."

Lucette gives her a silent thumbs-up. 

Anevia glues a flask of alchemist's fire to the top of doorframe. There's a bit of string attached that makes it so opening the door a little bit will do nothing, but opening it all the way will pull the cork out of the bottle, which is shaped so as to make this at least a mostly-directional blast.

Then she puts down caltrops in strategic locations under the water just past the door, where someone struck by the clingy fire might desperately try to extinguish it.

"Not worth our time blocking the door," she says out loud. "Do we still want to check the other one, or do we go back?"

"Let's check the other one." 

Then Seelah will work with her to unblock it again! (She almost moves the stones over to the door with the cultists behind it before she remembers about the caltrops.)

Wenduag presses her ear to the door for a minute. "Nothing but the splashing of water," she reports.

"Why is the water splashing?"

"Probably the same reason this place is half-drowned. The earthquake must have broken open a way to our lake, or one of the streams that feed it."

"There could be someone in there standing very still, let's proceed." 

Anevia picks the lock, and carefully nudges the door open.

The room beyond is large enough that the far edges are swallowed in darkness, and the water is even deeper than outside.

There is also a large water elemental about thirty feet past the door. It looks like a dark, angry octopus that's somehow swimming on top of the water. It doesn't seem to have noticed them yet, but it's hard to tell which way it's even looking.

...she very carefully and quietly nudges the door back closed!

"Large water elemental," she whispers to the others. "Not a good match for us in all this water."

"...Yikes. Well. That's somewhere for this water to be coming from." 

"But why's it here?"

"If the cultists could control it they would have tried to set it loose when they fought us. Instead they locked it in. Maybe the best way to stop them coming after us is to leave the elemental's door open before leaving."