Ambush at Commissioner's Hall

When The Ladies' Hiking Club first arrived in the Wandering City, they came across a poster advertising an event for Gavinus Garland's commissioning into the Tenth Royal Navy and investiture into the Most Chivalrous Order of the Stag. The event was advertised for the 22nd of Winterfall, 866WA at the Commissioner's Hall in Wakecrest.
The group, with Violet Verihendrion Miller and Peaseblossom in tow, attended the event at 8 PM and sweet-talked the hostess into announcing Beulah Garland, allowing them to cut the line. The hostess advised that Captain Carey was already inside but due to set sail immediately after the ceremony, so if Beulah wished to speak to him, she had better hurry.
The venue was packed. As the adventurers fanned out to look for Gavinus, a kitchen fire was soon discovered. Charity Milkbath took control of the situation along with Beulah, who excused herself after a moment as it began to sound as though the guests of honour were about to take the stage. Around the same time, Violet was spotted sobbing and running up crowded stairs with a crumpled note in her hand. She rushed past Vega Spritzer at the top of some stairs with Clytemnestra "Fanny" Glitters in pursuit. After some soft words, Violet agreed to speak to her mother alone in a reading room. She offered the note for her to read.

It's a Trap!

Sleep Glyph

All at once, the evening's events turned sinister. The note bore a glyph that cast Sleep on Fanny. She slowly passed out on a chaise-lounge to the sounds of a voice, half-Violet's and half-Azas' taunting, "Sorry, mama. Did I do a bad thing?"

Anti-Magic Shell

Charity, up on a tabletop in the kitchen trying to extinguish the flame, detected the sour scent of the fire oil they had used back at The "Lighthouse" and spun at hearing the sound of the chefs snapping the locks shut on the door and bar windows from the outside. She was locked inside a burning room, and that oil produces enough smoke that it was used by the Ladies and others as a screen against archers back in the catacombs beneath Bridlip.

Assassin

Beulah scoured the main room for any trace of her husband, but was abruptly forced forward into a passing waitress that spilled soup all over her. She did not notice the knife protruding from her stomach until it was withdrawn. She tried to scream but was unable to make a sound; tried to fight but could not spot her assailant. She charged up to the stage, waving her arms and inciting a panic from the sight of her blood. As the crowd rushed for the exits, Beulah managed to spot the one guest that was staring at her rather than the door: a slightly built rogue with wild eyes.
Run through, silenced and rotting from the inside out, Beulah sprinted to the exit.
Sensing something was wrong, Vega kicked in the door on Violet and Fanny almost as soon as it was closed. She shook Fanny awake and confronted Azas, who simply exhaled and left Violet's body. Determined to discover what happened, Vega studied the glyph. Fanny snatched it out of Vega's hands, chastising her as her eyes began to droop. Fanny insisted that something was wrong and they had to find the rest of the group. Vega procured a mandolin as a makeshift flail and followed the elfkin downstairs.
Charity reached out to force the bar windows open somehow -- but the fortunate fires that sometimes attended her were silent. She tried to use a smouldering apron from her attempts to put out the fire to burn down the door, but even trying to bring her Mage Hand from the fire across the room failed after a few feet. She packed the apron under the door in an attempt to burn it down, and kicked the door as hard as she could, with the smoke continuing to gather and weigh down upon her.
Violet and Fanny spotted Beulah at the base of the stairs, behind the crush of people heading for the exit. Beulah gestured frantically behind her at her assassin, who was gliding between wine glasses as she charged across tabletops towards her quarry. Without a second thought Fanny whipped out her shortbow and pasted the mousy rogue flat on her back with an arrow to the shoulder. The assassin recovered and sprinted behind Beulah, holding her like a shield from her colleagues. She produced a second, vicious-looking dagger roughly twice as large as the thin, needle-like blade that had run Beulah through.
"Whoo!" yelped the assassin, "Carrie", grinning as she pulled back Beulah's hair in mock-intimacy. "You're a slippery one, babe."
She drove the larger blade up between Beulah's shoulder blades and the poison began to work stronger than before. Beulah screamed in silence.
The assassin pulled back, knife in each hand, and began bouncing low on her toes, edging towards the nearest table, ready to dodge whatever the newcomers had to throw at her.
Vega rushed down the stairs, snuffing the fire under the kitchen door as she went.
In the melee that followed, Beulah spun to fix Carrie with a withering glare that positively cracked her up. Beulah managed to get out of harm's way with help from Violet's fledgling healing abilities. She proceeded to knock down the kitchen door together with Charity, who managed to escape. In the interim, Fanny caught Carrie across the cheek with another arrow, which prompted her to heave a heavyset guest at her and to vanish into the crowd. A few moments later, Fanny bent down to spill some ball bearings on the ground to prevent the assassin from leaving the room. As she righted herself, knives plunged into her hips on both sides and a snickering voice said into her ear, "Oh my God, you're not too good at this, are you hon?"
In retrospect, that was probably a mistake. Vega cast some kind of hideous black magic on herself and charged forward at the black-clad figure, driving a Dragontooth dagger deep into her ribs. Acid mixed with necrotic rot and she stumbled backward, trying to steady herself on the ball bearings. She cried out in only barely feigned desperation, "Brother! Brother, they're being so mean -- they're killing me!"

Artillery

The stairs shook with impact. Then they shook with another, under the heavy steel boots of an impossibly large man. Thick hips appeared under a slotted leather skirt and studded armour clanked in treble above the terrible bass of his descent. A worn buckler and well-tested spear came into view, and an auburn mane clung to chest and shoulders knotted with muscle like a rootbound plant. Once this brother of hers, Yorick fully came into view, it was difficult to know what was causing the sick pit of dread in the ladies' stomachs: the ferocity of his gaze towards them, or the colossal sixty-pound warhammer slung to his back.
Detecting the fragile healer at once, still glimmering with green aurora, Yorick bludgeoned Violet with his shield. She was immediately knocked unconscious, falling down a flight of stairs without the ability to raise her hands. Beulah tended to her urgently as the mountainous man crashed down the stairs.
The urgency of the situation immediately becoming apparent, Vega and Fanny both stabbed Carrie once more, with Fanny driving the dragontooth knife up through her chin. She landed on the ground amidst the horrified screams of panicking guests, blood pooling rapidly around her.
Charity made a break for the exit, a necrotic hand rising from the ground behind her and grasping ineffectually at Yorick's nether regions. Beulah, Fanny and Violet ran. Vega paused. She knew better than to leave an enemy like this -- skilled, motivated, merciless -- to catch up with them another day. As Yorick reached the lobby, he turned to see Vega Spritzer, priest of Eldath and late disciple of the God of Death, driving Carrie's own dagger deep into her heart. A glowing spear pierced the assassin's throat.
Yorick froze. Vega broke for the door. Some muttering in a Greyshore accent crossed the threshold of the Hall and somehow Yorick was compelled to laugh. His grief soon overcame the forces invading his mind, and he rushed to catch Vega, screaming and crushing her into the wall, leaning on her through his shield. He jammed his spear through her leg as she kicked, twisted and ran. Blind with rage, he began swinging his warhammer madly. Vega easily dodged away, only at the stairs catching a harmless impact on the flat of her armour that carried her out into the hallway garden. She joined her friends and ran. Yorick screamed for the evacuating guests to stop the murderers, offering them wealth if they did so; Fanny did the same, confusing the group into stasis until Beulah exhorted them to defend her, to defend Tenthun and the arts and beauty by turning on the hulking figure in the doorway. A few equestrians reversed course to make inquiry, and the women fled to the train station.

Aftermath

Yorick returned to the burning hall. The tapestries were going up and the smoke was getting thick. He moved forward, wading through grief thick as water. He paused at the doorway, instinctively averting his eyes from an upturned boot. Something gripped his shoulder. Someone said something. Someone else seized a wrist.
This was welcome. This was easy, familiar. Exposed ribs here, too much forward momentum there. Weight on a leading foot that could be held in place. The impacts were embraces, sternums and hips giving way like pillows. It was over too soon and he was alone again, joists cracking under the heat overhead.
The legendary gladiator did not know fear. It was a luxury he was never afforded, and it left him early in life. He came close enough to reveal a knee. This hesitancy, this thrill of sickness deep in his chest was unfamiliar. His eyes began to sting, from the smoke. He willed his boots onward, turning the corner. The walls were blazing. There she lay.
Somewhere over his shoulder a portrait crashed to the ground. The smoke was making it hard to swallow. For just a moment the air was rancid and dusty, he was fourteen and at the pit-gate, fighting-pick weighing the skirts down off his slender frame. His mouth filled with the carbon from the moist chicken, he remembered the fingers in his hair, the pale arm dangling down through the bars.
They made him laugh at her.
He lost himself.
When the noise subsided he was with her again and the heat was unbearable. Threads of their congealed blood pulled apart and snapped as he raised his head from hers. He brushed her hair from her face, closed her eyes and hardened. The word cowards scarcely escaped his teeth.
The door frame came down on his shoulder and he shoved it aside. He had to get her out into the fresh air, this wasn't a safe place for her.
Moments later, the Quattrociocchi children were outside at night again. They turned and walked into the gardens.

What the Hell Just Happened?

Here is what we know:

• No one in the building seemed to have any idea who Gavinus was or when he was coming other than the woman at the door taking names.
• The hostess alerted to the kitchen fire took no steps to prevent or mitigate it.
• Violet's demonic voice was the same as what they heard from Peaseblossom the night before: it was undoubtedly Azas.
• The image on the posters seems to have been copied from the portrait Beulah commissioned from the artist at Blackfriars.
• The portrait of Gavinus did not arrive even though Fanny's did. It seems safe to assume it was intercepted.
• Reghyxesh said three people had inquired about Fanny since their arrival: Thalia Overmere, General Kuzoh and a third individual.

There were surprisingly few Tenth guests at the party. In retrospect, there were a lot of Hobbit and Corran accents, and both Carrie and Yorick had thick Maulden accents placing their origins in the vicinity of the metropolis of Correhal. It's hard to get away from the suspicion that one or both of the Overmeres had something to do with this.

Who Did This?

If the events at this party are related, then someone:

• Used the false promise of Gavinus' presence as bait;
• Prepared and circulated posters for this 'event' before the Ladies even arrived on the Zaratan;
• Split the party;
• Hired an assassin with the ability to Steal Voice to go after an Eloquence Bard;
• Used fire oil to set a lethal hazard in a kitchen that seems to be rigged to prevent magical 'accidents' from occurring; and
• Possessed Violet to cause an emotional scene that drew Fanny away from the team, equipping her with a non-lethal glyph that, if not for Vega, would have taken Fanny out of the action.

I mean, I don't want to say it was Tumner, but it was probably Tumner.

Update: Meeting with Decima Overmere

Following the Club's conversation with Decima Overmere in The Non-Canonical Demiplane, it is now beyond question that Decima was the strategist behind the ambush, intercepting Beulah's commissioned portrait of Gavinus to use as a poster luring them to a location on a specific date and time, and providing a false sense of security by doing so outside Corran territory. She infiltrated Thalia's guard with her own and hired her personal assassins, the Quattrociocchi siblings, to eliminate them and to frame Thalia for the hit in the event of failure. (She is seemingly unaware or heedless of the extent of the relationship developing between Thalia and Clytemnestra.) She made specific provisions to separate the Club and tailor their traps to their weaknesses:

• She met Azas at some point and somehow conscripted him to possess Violet Verihendrion Miller to peel Fanny and Vega away from the main floor, then to separate those two under the pretence of engaging in the kind of private heart-to-heart talk that Decima somehow learned Fanny craved. "Violet" held a sleep glyph that rendered Fanny unconscious and presumably available for interrogation and another crack at the Lantern.
• She learned of Vega's interest in Violet and removed the healer from the main targets of the assassination attempt. It remains notable that while Fanny had to be taken alive, there was no specific plot to kill Vega, who is as disposable as Beulah or Ch---.
• She was familiar with Ch---'s inability to avoid being sucked into kitchen duty, commissioning actors to start a magical, asphyxiating fire in the Commissioner's Hall kitchen and to abandon it, leaving Ch--- with the mess. She had metal panels installed over every opening with exterior locks to trap Ch--- inside and positioned Antimagic Fields on both sides of the room to preclude any of the "coincidences" for which the Halfling is becoming known.
• She presumably supplied Carrie Quattrociocchi with an enchanted dagger capable of silencing its target, with instructions to commence the attack by silencing the Eloquence Bard and rendering her helpless.

In the event the assassination was unsuccessful, Decima correctly assumed the survivors would return to lick their wounds at their base at The Lamplight Inn and seemingly dispatched a Gnomish explosives expert to booby-trap their room. Her intelligence failed her on this point, however, as she was unaware that the room was already booby-trapped. He was blown back on to his own charges, blew himself through the roof, and fell back into their hallway in pieces. Decima's backup plan was thereby foiled.
Pretty good plan though.

Hearts mended and sun in the sky, our adventurers made their way down to the Overcroft. On the way over an unremarkable bridge, they encountered a polite young Hobbit nobleman in a square velvet hat. He made no impression upon them, though they certainly made one on him. The five of them fit the description perfectly. He made haste to Bridlip to send a pigeon.

-- Chronicle, Chapter II, Part VII