(Rhayna: Yes, there is ample fungi within 500' and Rhayna could move to almost any location in the tunnel from her present location)

(Shall I assume that Kaylyn, Rhayna and Pax are all disguised as drow females, while Kirin and Sekkar are males? Are you all generic-looking drow or are there any specific priestesses, mages, warriors, merchants, etc?)

Would assume Sekkar plays a simple warrior (male, yes), big and quiet. Just following orders here.

“Before moving out, please give me a minute.”  Rhayna will find the closest fungal patch, and use her Fungal Stride.

(Rhayna will just scout the place where they are as much as possible. Popping in the next patch, and so on. Like she did in the Whorlstone Tunnels.)

(generic drow, nobody specific)

The female drow that is actually Rhayna promptly glides right into the nearest large mushroom and disappears from view. She is only gone for less than a minute, but when she returns she reports that most of the drow moving along the tunnel appear to be merchants or couriers, some guarded by warriors, and a few by mages. Two drow patrols were also seen, but their attention was focused on the many non-drow slaves that accompanied the groups doing all of the carrying - mostly orcs or goblins, a few quaggoths, and a single bugbear.

(Rhayna, if there is anything specific you were looking for then let me know and make an Investigation roll. If you were hoping to be discreet then also make a Stealth roll, unless you are happy popping in and out of mushrooms in full view of the drow)

Feeling safe in the disguises, and not wanting to waste time on the spell's duration, the group slip through the grotto and into the main thoroughfare. No-one seems to pay them any heed, with most of the male drow averting their eyes from Kaylyn, Rhayna and Pax, and most of the females giving them a brief and respectful nod (although there is no cordiality in the gesture.) The softly glowing purple/green of faerzress is thick here, further indicating why teleportation this close to the city is so difficult. The small fungal haven to which Vizeran teleported the group is indeed a very rare exception, and a particularly useful way for the group to avoid days of travel. Two drow patrols do in fact pass the group, one of which is a pair of warriors riding on large lizards. They too glance at the group (with less deference than any of the common male drow encountered so far) but see nothing amiss and pass on. The single mile to the outskirts of Menzoberranzan seems like it is passing blissfully without a hitch...

Shortly the group find themselves in a line of travelers waiting to pass through the final archway that leads into the city proper. Several guards can be seen up ahead, stationed on small fortified outcrops of rock with large crossbows. More armed guards are visible strolling slowly along the line of travelers or languidly leaning up against the tunnel walls. Craning to get a look at the cause of the delay, the group can see that although drow and their slaves are exiting the city without impediment, there seems to be some kind of checkpoint for entering. The side of the passage for entry is manned by a single male drow mage, who seems to be operating a strange contraption suspended within the large archway. It appears to be some kind of spherical contraption, clearly magical, with an exterior framework made of ornate silver, housing some kind of whiteish orb. A few steps closer and the nature of the orb becomes clear, if for no other reason than the group have only recently encountered an identical object: the central eye of a beholder. Apparently to enter the city, every traveler must pass beneath this contraption...

The passage is about 120' wide, divided in two by a tall row of metal pickets, with the left side for entry to the city and the right side for exiting. The archway is about 80' high, with the beholder eye suspended 30' below that (so 50' above the floor) and covering the left side of the passage. Other than the mage and the two drow on the turrets, there are about twelve drow warriors on the left of the passage watching the queue, and another eight on the right side. (This doesn't count those drow accompanying the travelers.)

"We need a distraction." Sekkar suspected he will have to repeat these words many times in the near future. "I can try to shoot the eye so you all get through, but it would take some time for me to return after." He did not add "if I can" but that was obvious.

Pax growls, "Vizeran is useless.... or this is new. Hold on the distraction for a moment."  She calms herself and begins glancing around the main gateway area, her eyes examining the various details and measuring options.

What material is used to suspend the eye from the ceiling? How does the mage appear to be operating it?  Does Pax know if Dimension door will work to get through the gate and into the city from here, or does the faerzress prevent short range teleport as well?  What is immediately beyond the gateway into the city?  Is it a large open area or are there alleys / buildings to move behind? Does the gateway close? Is there an open gate that can be swung shut?  What does the edge of the cave look like here?  Plans ripple through her mind as she considers the options. How far from the front are we? How many are behind us? 

The approach tunnel widens leading up to the archway, reaching a width of about 200' right before the entrance. The 40'-wide space on either side of the archway is mostly taken up by guards and their accoutrements (a few tables and chairs, some food and wine skins, some weapon racks with crossbows and shields). The ceiling is only marginally higher than the archway itself. There doesn't appear to be a close-able gate within the archway. The barrier and the contraption appear to be recent makeshift additions. 

The contraption itself is made of slender silver bands that surround the eye, but it is suspended from the archway by a mundane metal chain. The mage doesn't need to manipulate it too much as most people simply pass under it, but there is one long rod that attaches to the contraption, which can be pulled to angle the eye-beam a little if needed, or twisted to close a small shutter and turn off the beam. 

Immediately beyond the gate can be glimpsed the open space of the cavern of Araurilcaurak, as the drow call it, in which the city of Menzoberranzan lies. The great glowing pillar of Narbondel can be seen in the distance, but immediately beyond the gate  (starting within only a dozen feet or so) are the merchant stalls and pleasure houses that surround the stately residential district of Narbondellyn. So yes, there are street stalls, alleys and buildings of a varied kind.

There are 20 people in the queue in front of the group, and only three behind. The line is moving slowly enough that some have temporarily laid down their burdens, and are talking and mingling, so it isn't exactly the most rigid queue.

Dimension Door will work outside the city, although with increased risk of mishap due to the faerzress. However, it won't work if the destination is inside the gate, nor will any spell that uses the word 'teleport' in its description (e.g. Misty Step).

Kaylyn follows with the others.  She has chosen to look like a mage in her female drow disguise.  As the group approaches the gate the item in question becomes a concern.

She tries to see if she understands what it may do.

Arcana 13

"I could simply suggest a number of people in line try and tear it down.  Drow are difficult to charm but it will only take one or two to fall under the spell.  And my magic is strong enough that I'll get more than a few of the twelve.  It could be quite fun to watch."

(Can Rhayna use Channel Divinity: Read Thoughts on the drow mage?)

(Channel Divinity: Read Thoughts. As an action, you can use Channel Divinity to choose one creature that you can see within 60 ft. That creature must make a WIS saving throw (19). On success, you can’t use this feature on it again until you finish a long rest. On failure, you can read its surface thoughts while within 60 ft. for 1 minute. During that time, you can cast suggestion as an action on the target without expending a spell slot.)

Pax muses out loud, "I wonder who he closes the iris for. Clearly someone of a certain rank can pass through without being...subjected to the eye. If we knew we could demand he close it for us." She turns to Kaylyn, "Yes, if you could suggest them to charge the gate, that could afford us the distraction we need to get through." 

Sekkar grinned. "Do it!" The group could use some fun and the show promised to be hilarious. In the worst case, there seemed to be an option to "turn the eye" - even a bit would be enough to slip under it unaffected, no need to close anything.

Even in her rare dull-witted moments, Kaylyn can deduce that a central beholder eye magically preserved in a silver enclosure must be used to produce a permanent antimagic field, the details of which Kaylyn is familiar with. However, in order to be close enough to operate the contraption, the mage must be standing within the field themselves. At first this seems strange and a bit counter-intuitive, but seems less so when Rhayna realises that she can't target the mage directly with her divine magic. Clearly the mage can switch off the field with a quick twist of the hand if spellcasting is required, but he is otherwise immune to magic effects from outside. And anyone that was affected by any kind of enchantment or other magical effect would be stripped of such effects were they to come within the range of the field. It is quite ingenious really!

"not if they all get "angry" and shoot the thing from afar... Just saying." The idea of taking down the eye looked more and more attractive if only for it's difficulty.

Quickly eyeing twelve people in the line ahead, choosing first the mage who operate the eye, then armed guards who are visible strolling slowly along the line of travelers or languidly leaning up against the tunnel walls. She'll choose other men in line if she needs to fill out the twelve.

She then casts Mass Suggestion. With her rod in her hand she quietly speaks the words of magic and then calls out in undecommon so they can be heard "Destroy the spherical contraption made of ornate silver!  It is an abomination! to Lolth!"

She moves to stand behind Sekkar, hoping his height will block her view and maybe no one realizes it was her that actually spoke.

Deception if needed 12

As soon as Kaylyn as cast her spell, hoping chaos is about to erupt, Pax reaches out and touches Kaylyn, Kirin, and Rhayna, and casts Invisibility on herself and all of them.  (5th level slot)  

"Sekkar, you're a ghost, you don't need the magic.....", she mutters, and then, "...remember folks, no attacks and no spells or you become visible, lets go out the 'in'..." 

(If a appearance can specified, Rhayna chooses to looks like a junior priestess like Asha. Also, can Rhayna use her wand, and shoot a glob at the eye contraption?)

I missed that the mage had to be in the anti magic field to operate it so she won't target him.

Rhayna, If you glob it you'll become visible.  Let's see how the suggestion play works out and see if we can get through the gate that way. 

(Wow, DC 20 is epic. I don't think any of them have a WIS modifier, but they do get advantage. I'll make the rolls now, then write the post later on when I'm at work...)

17, 18, 15, 20, 16, 15, 17, 20, 18, 6, 7, 15

Kaylyn's celestial gifts are powerful indeed, even sufficient to overcome the natural resistance of the elves to enchantment. Many heads turn at Kaylyn's initial outcry, looking to see the source of the commotion, but their attention is drawn away immediately as the two drow on the small towers turn their crossbows toward the contraption and fire off a bolt each. The mage looks up at the them with horror and begins babbling and gesticulating angrily.

Meanwhile, four of the guards closest to the waiting column draw their swords and charge toward the mage, looking up at the eye-contraption. They pull up short just as they enter the field, and begin looking around in confusion, lowering their swords. One turns and runs back toward where Kaylyn's voice was heard, but as soon as he is outside the antimagic field, the enchantment again takes hold and he again runs back toward the mage, stopping once more in indecision as he again enters the field.

While this confusing drama unfolds, three more guards from the right-hand side of the tunnel run toward the stack of weapons and pick up a handful of javelins, which they begin hurling at the eye-contraption. This sends the mage into an even wilder fit and he twists the handle to close the iris, most likely to protect the precious eye as much as to allow himself to cast his own spells. Immediately the four sword-wielding guards resume their eye-stabbing crusade and attempt to wrestle the handle from the mage's hand. The poor mage is forced to cast an abjuration spell on himself to defend against the guards.

One of the guards manages to grab the handle and yanks hard in an attempt to rip the contraption from the ceiling, but manages only to open the iris again. The mage's shield spell vanishes, and the sword-guards stop wrestling him. The mage begins to realise what is happening, but as the crossbow bolts and javelins continue to slam into the eye-contraption, he again grabs the handle, closes the iris and attempts to cast more protective spells.

Amongst all this disorder, the drow both entering and leaving the city scatter in chaotic mayhem. Drow merchants scatter in all directions, some running back the way they came, while others force their way through to where they intended to go (either toward or away from the city). One of the goblin slaves is trampled by a giant lizard. Three orcs rip their shackles from their chains and begin pounding their drow overseer. Two young drow run over to the guards' weapon racks and start looting the choicest pieces. And four drow simply stay in place and gleefully watch the havoc unfold, cheering the guards that have apparently turned on the mage, and laughing and pointing at the commotion around them.

Amongst such tumult, it is a simple matter for four invisible (and one visible but unusually aggressive) pretend-drow to slip through the archway, avoiding the intermittent field of antimagic, pushing a few hapless slaves or other drow out of their way, and into the streets of Narbondellyn.

(With all the chaos and four of the party invisible, there is a chance someone becomes separated from the others. Everyone make a Perception check. If the total equals 100 or more, everyone finds each other. If not, then the one rolling the lowest, or anyone rolling less than 10, gets separated.)