It would be nice if Anton's inability to hit things was a surprise. Oh well. Acid Splash?

Yes! She hits the first one cleanly, and the can hear the extra sizzle where the brimstone isn't. Success. Now she just needs to keep that going...

Anton's grey beam washes over the first zombie's head. It burns with invisible fire and turns to ash. The headless corpse slams into the floor. 

Mika throws a dagger, again. He misses, again.

He is keeping pace backing up with the zombies, though.

The zombie sprints forward—

It slips on the marbles and goes crashing to the ground. Its arms move unnaturally, trying to push itself back up.

Marbles! Yaaaay marbles. No zombies hitting anyone this time, preparation is a wonderful thing. And Anton even managed to hit something! Disrupt Undead is impressive when it isn't aimed straight at the rock.

Unfortunately, this means it's harder to hit with a Splash... but harder doesn't mean impossible. Acid to the head, complete with that bit of extra sizzle.

Julio flings more acid. It hits the zombie's back!

He backs up further.

Mika throws his last dagger. It misses. "Damn it!"

The zombie shakily manages to get upright.

Acid! And, more importantly, staying at least fifteen feet from the zombie!

Perhaps she should have prioritized aiming her acid more. Oh well. As long as the zombie can't hurt them, her aim doesn't need to be that good.

Anton's disrupt undead scorches chunks of flesh away from the zombie.

Julio flings another glob of acid. It melts part of the zombie's face off.

Mika is all out of daggers. He draws his sword and backs up.

The zombie is not looking good. It charges at Mika, but its great slam goes wide.

She shoots for it. Aiming around Mika is a challenge, but it is off-balance from the charge, and that gives her just the moment she needs to hit it with her Splash.

The zombie seems to come apart when her acid hits. Its rotten organs spill out onto the floor, and it collapses.

Mika takes a few breaths. "There any more of 'em!?"

"Not immediately, at least. I don't know exactly what we'll see inside."

And this time, there will be no need to wait overnight for them to limp back out, because nobody was even injured! Preparation really does make a difference, it's kind of impressive.

She starts gathering up the marbles. No need for any of them to accidentally fall if they have to run out quickly for some reason.

Anton and Julio head inside Matei's lair and start looking around for loot. "Nothing magic atop the desk, but there's a bunch of stuff inside it."

...

"Oh, that's nice. Look at those books. And those gems. And that ring."

"Check for traps before you go poking at anything in the other rooms!" She's still gathering marbles, so she can't actually make sure they do it, but surely they're sensible enough to not set off anything too obviously, right? And the dresser should only stab them if they open it, they'll handle it.

"I looked for magic!" Anton yells back "and we can keep to this room for now."

"Good plan!"

Once she's finished with her marble collection, she goes in with them. "I see some magic in the dresser in there? The ritual circle looks ominous, but I don't see any auras."

The party spends a little while going through the rooms of the lair. They get everything from the desk in the main room. Mika is only able to safely get the first drawer of the bedroom dresser open, the others are trapped in a way he's not confident he can disable. There's nothing of interest in the ritual room, as far as they can tell.

Anton packs the loot into his bag.

Anton leads them through the caves at a brisk pace. They travel back through the winding caves the way the came, and across the rivers in the large cavern, and into the oddly-shaped tunnels.

They're about halfway through the tunneled stone to the maze ladder when Tencednil's familiar becomes alarmed.