As the party of adventurers traversed the stone corridor into which the staircase from the upper world had led them, Lexi was continually staggered by the fact that everywhere she looked, despite the somewhat decayed state of things, the passageway bore the clear and unmistakable signs of having built by some intelligent race. With walls made of cut stone blocks, broad paving stones underfoot, and a uniformly slightly vaulted ceiling above, the corridor was no more naturally occurring than the temple from which the group had so recently come.

Luella had been confident that this corridor was the correct one to take from the central foyer-like room in which they had initially began their exploration of the subterranean world. However, although the foyer had presented several such passageways, this corridor had yet to yield any side passages, adjacent rooms, or much of anything at all except the odd alcove with the uninterpretable ruins of what was once a statue. Despite this early monotony, the sense of dread that Lexi felt upon their initial descent did not abate. Rather, it built slowly with each step the paladin took.

“Who built all of this anyway?” Lexi whispered, wincing as her voice echoed unintentionally through the passageway’s hard stone.

“No one knows for sure,” Luella answered softly, her subtly inhuman register not creating quite as much resonance as Lexi’s. “Everyone has their own pet theory, and you’ll find that some of the races with large settlements down here will make claims to being the builders. But, none of it really holds up under close scrutiny. The dungeons are older than any civilization currently living down here, and anyone who tells you otherwise is probably just trying to pad their claim to a chunk of territory.”

“What kinda races do live down here?” Danica asked excitedly. “I’ll bet there’s all kinds of weird stuff creeping around these spooky dark halls. Maybe we’ll meet a lamia! Or a mind flayer! Or a dark elf! Or—”

“Hope that we meet none of those denizens, little one,” the mothgirl said sternly, cutting Danica’s exuberant imaginings short. “I have been unfortunate enough to encounter many such foes in the decades I spent in the world below. There are precious few races who haunt these corridors who would be remotely friendly to us. And, even fewer still would be foes with whom I would wish to cross blades.”

“Is there a particular reason that this section is devoid of such inhabitants?” Samantha asked pointedly. “It would seem to me that an entrance into the upper world would be a coveted region by any of the evil races who might be interested in conducting raids on the surface.”

“Yeah,” Lexi agreed. “We’ve been walking for like fifteen minutes down here already, and we’ve seen nothing moving except our own feet.”

“There are two reasons for that,” Luella answered, a slight catch in her voice perhaps indicating that this was something she was unhappy discussing, but nonetheless powered on through. “The first is that the portal through which we entered does not operate in both directions. It can, under the precisely correct circumstances be used to enter into the dungeon world, but it does not function as an exit. There are many such ways to leave the labyrinth,” the mothkin continued, hoping to assuage any rising fears about being completely trapped in the corridors. “However, I am not aware of any portals which are bidirectional — which tends to make such places not particularly desirable for most underworld races.”

“The emphasis you placed on the word ‘most’ makes me wonder who does find this to be an advantageous locale,” Lexi said.

“Well, the way entrances work here,” Luella continued. “Is that each one will almost always have a guardian. I don’t know for certain if this one does, since I’ve never entered through this passage. But, unless the portal guardian has already been killed by some other adventurer, then it’s likely that we’ll find this way in to be guarded by something Danica might describe as interesting.”

“So, these interesting critters just…what…hang out in these areas like it’s their job or something? I mean, that just seems weird, right? Like, unless something else is making them stay in place, what’s to keep them from just getting up and going literally anywhere else?”

“That is one of the mysteries of the dungeon world which all but refutes any claims to manufacture or ownership by any of the natural races,” Luella answered.

“Natural races?” Lexi asked.

“Y-Yes,” Luella replied. “Guardians will never belong to any of the humanoid, goblinoid, or even beastkin races. Invariably, they come from the stock of supernatural races which most of us would term monsters.”

“Fuck me gently with a chainsaw,” Lexi muttered. “I figured we’d be seeing some action pretty soon down here, but I was kinda hoping that we’d have some kind of break. Can’t be helped though, I guess.”

“Will we have any forewarning before encountering this guardian?” Samantha asked. “It would be good if we were not caught unawares by whatever this creature might be.”

“Actually, it’s funny that you should ask,” Luella said. “See that vaulted arch at the far end of the tunnel, with the big set of double doors?”

“Whoa, yeah, I do now,” Lexi said, so absorbed in the conversation that she had not noticed the structure some hundred yards ahead until prompted by the mothgirl. In the low light of the twilight vision provided by the Starsight Gem, it was visible. Although, at such a distance, it was just barely so. This bit of information told Lexi that mothkin likely had significantly better night vision than that which the gems provided.

“Even I can just barely make it out from here,” the mothkin continued. “But, there’s an emblem on the keystone with a pair of crossed keys. Those always identify guardian chambers. So, if we’re going to find anything at this juncture, it’ll be behind those doors.”

“Alright then,” Lexi said, drawing her enormous broadsword from across her back. “Tits up, girls!”

Reaching the doors, Lexi saw clearly the emblem carved into the arch’s keystone which Luella had mentioned, and pair of crossed keys, each one looking like what the paladin would have recognized as an old-timey “skeleton key” back on Earth. The doors themselves were the first things she had seen in the underworld so far that was not made of stone, and as such stood out quite clearly the closer their approach came. Each panel was an enormous slab of some kind of dark stained wood, like mahogany or walnut. Huge brass handles in the shapes of hanging rings were affixed to each door, and the doors themselves were just barely ajar — no more than a fraction of an inch — but enough to look as if they were asking the approaching adventurers to open them up and see what lay beyond.

“You’ve done a good job so far in getting us here,” Lexi said to their mothkin guide. “But let me take the lead if there’s a chance something ‘interesting’ is waiting to greet us behind the doors.” Luella nodded in assent, clearly as nervous as the rest of the party as to what they might find. “No sense in pussyfooting around,” the paladin said to herself as she pulled back on the brass rings, throwing the pair of doors wide open with a cacophony of creaking hinges and crashing wood.

What the fuck is THAT!?

The double doors opened into a wide square chamber, within the center of which was an incredibly soft looking pile of pillows containing a creature which — had its eyes not been wide open and staring directly at Lexi — the paladin would have assumed from its posture was fast asleep. It was not a creature that Lexi had ever laid eyes on in either this world or her past life, and it took a moment for her mind to flip through the catalog of fantasy monsters to figure out exactly what she and her friends had just walked in on.

Despite an array of bestial qualities, it was clearly not a beastkin, whose general physical forms were typified by an animal-influence humanity. This creature, on the other hand, looked to Lexi more like some kind of pastiche of elements thrown together at random, without any of the unifying harmony that she had observed in the various beastkin with whom she had come into close contact. Below the waist, the creature’s body was entire that of a black panther, with a pair of powerful looking legs terminating in paws far larger than Lexi’s own hand resting comfortably beneath thick haunches. It’s long sleek tail curled around its panther feet, the tip moving up and down lazily as the creature observed the intruders silently.

From the waist up, the creature was largely human, but with two extremely noticeable departures. Completely nude, the futanari saw that they creature was clearly female, and was blessed with a tight wast and an extraordinarily nice set of tits. The way she was lying down, her torso was suspended just enough that her tits rested atop her forearms, looking deliciously soft and pillowy to Lexi. The skin covering the creature’s human parts was a very pale gray, shot through with dark purple on her nipples and lips. Her humanity ended at her forearms, where the graceful curve of the female upper arm gave way to the black fur of a panther, with each limb terminating in yet another enormous cat’s paw.

A pair of large black feathered wings sprouted from behind the creature’s shoulder blades, folded up to rest atop her back as she lay there. Like her torso, the creature’s head was fully human, with a single exception. Beneath the soft bangs of the sleek black hair covering her head, a pair of luminous red eyes stared out at Lexi — a fact she would learn later was indicative of the heat-sensing infravision common to many of the creatures native to the subterranean layers of Aeternia.

Stretching her front paws forward, the creature thrust her hips up in the air, arching her back to stretch, the biggest difference between her and any house cat being the enormous pair of tits which hung down from her chest as she stretched. Momentarily, the creature sat up, the posture again reminding Lexi very strongly of a house cat, her back haunches seated on the ground, and all four paws planted in a row in front of her, with her head and torso being upright. Stretching her black wings out only to refold them behind her back again, something in Lexi’s mind finally clicked, and she remembered what this creature was called.

Sphinx!

Somehow, putting a name to this creature did not serve to inspire any confidence in the paladin. As the creature sat up, Lexi could feel the raw power emanating from it, quite unlike anything they had faced before. Even the tentacled monstrosity which had nearly decimated her entire party and ultimately killed Gretel did not exude the sensations of barely contained intensity as did the sphinx. Although it made no ostensible move against the party to prevent their passage, Lexi knew instantly that the pair of matched doors behind the sphinx were — at the moment, at least — completely out of reach. This was not a creature with whom she wished to fight, that much was perfectly clear to the paladin.

Hold the fuck up, Lexi thought to herself, as recollections of sphinx lore flooded into her brain. In most RPGs, you don’t actually have to FIGHT sphinxes. This all fits though. They’re super powerful, and will guard special places. But, they’re more interested in posing fucking RIDDLES to people than they usually are in fighting. So, as long as the architects here are following along with that kind of paradigm, we just might get out of this will all of our limbs attached.

“This is bad,” Luella whispered to her, quivering where she stood. “We can’t fight her. Even the four of us would lose for sure.”

“You’re right there,” Lexi agreed quietly. “But, don’t sphinxes just ask you riddles?”

“…”

Shit!

“M-Maybe things are d-different above ground,” the mothkin said nervously. “But the ones down here are reputed to issue a test to any travelers who would pass through the chambers they guard. If you pass, then they’ll let you through. If you fail…they’ll…uh…eat you.”

“OK,” Lexi said shrugging. “That’s not too different then. What’s the test?”

“Your friend is well informed!” came the purring cat-like voice of the sphinx. “If even one of you brave adventurers can pass my test, then all may travel safely. But, if your champion should fail, then you shall all be devoured.”

Lexi gulped audibly, her mouth suddenly dry. “What’s the test?”

“It is a test of sexual fortitude, the roles of which are quite simple,” the sphinx replied casually, her tone belying the seriousness of the conversation. “We fuck, and whomever cums first loses.”