The Shadow Market

Alice looked with wide eyes at the looming city. The journey, a brief sojourn through the Shadowfell, had been dour and full of dread. She had gotten so frightened at one point that her mother had cast a spell on her to quench her emotions entirely, so she'd spent most of the trip in a dissociated haze. The spell had since worn off, and the horrors of what she'd witnessed crashed in on her. Apparently they were near enough to safety that Nereia didn't think to use another spell.
The floating city hovered overhead. Nereia raised her hands in a gesture - the first two fingers of both hands high with her thumbs spread wide - and intoned the incantation. "Sui or, sui dad!" The Elvish lilted from her lips with a musical beauty quite out of place in the dolorous surroundings. The ground rumbled. The two robed men with them, Nereia's guards, looked briefly terrified, and nearly jumped from their skins when eight Shadar-Kai warriors appeared in puffs of acrid black smoke.
"State your business!" the captain commanded. The others held glaives leveled for business, but he held a bearing promising violence with no such obvious source.
"My business is mine." She tossed him an insultingly small coinpurse. 
The captain scoffed and looked inside. His pale flesh drained even more, and he poured a handful of perhaps a half dozen red coins into his hand. He held one up to better look at it. Alice saw the relief of the coin; a man's face. It was animated, straining as if to free itself from the coin and screaming silently in horror and panic.
"How's a Clownworld witch get her hands on six soul coins?"
"I have almost a hundred. I'm no mere witch. Am I welcome back into your city or am I collecting eight more coins and entering as a criminal?"
The captain smirked, then looked at the coins again. With practiced ease, he slipped them into his own purse and wove a complex gesture. A tear ripped through the air, then widened to show the city's streets. Without further acknowledgment, Nereia strode through. Without much else to do, her retinue followed.
Alice was shocked. After the sightless, colorless journey, the streets of Blythopoly was almost insulting. Maddening angles in defiance of natural laws, insane colors splashed in clashing patterns, and every surface covered with either bright fabrics or intricately carved art. There were tumblers, street performers, at least three celebratory mobs, and breakout street games from dice to cards to something involving a fleshy ball and a high stone hoop. Even the smoke pouring out of the chimney fires was thick and colorful. As Alice watched one of the vendors operating a grill, he reached into his pocket, pulled a pouch from it and threw the pouch into the fire. The flames immediately turned a dazzling purple, and the smoke glowed brilliant crimson. This elicited a cheer from several Shadar-Kai children. The sausages glowed as well, seasoned by the smoke.
Blythopoly didn't smell like any city Alice had ever entered. There were the usual smells of cookfires and garbage, but the smell of hot pavement was not present, nor was the usual smell of the press of bodies. The scent of the inhabitants was sweatier and more desperate, more like the nervous and frenetic sweat of a tournament game or the dances of the young and lonely that Alice had occasionally snuck into. 
The sound was deafening, and of every description. Angry, joyous, ecstatic, insane, rational, bartering, all possible conversations at every conceivable volume appeared to be going on in the street at this very moment.
A Shadar-Kai man jostled into Alice, having been shoved aside by a bearded monstrosity. With a twinge of horror, Alice realized that she was looking at a Barbezu, a Bearded Devil. It barked something at the man, who laughed merrily.
Alice didn't see the catalyst for what happened next. Perhaps the devil didn't appreciate being mocked. In an instant, the two were fighting, glaive to cutlass. The Devil never lost its grim demeanor, and the shadow elf never stopped giggling. With a whirl, the devil skewered the elf, who coughed one last chuckle before he expired. In moments, the sight of his body was obscured by the press of bodies going about their day. Nobody seemed to mind, so Alice hurried after her mother.
Nereia looked at her daughter with a cold glint before approaching a vendor. The next few hours were a blur of color and sound, punctuated by exotic materials paid for with those strange, silently screaming coins. Their guards became porters, hauling the goods through the city. 
When the 'day' was done, they found an inn to rest before returning home. The sign was as gaudy as the rest of the city; A skinny jester with a terrifying rictus grin, a green-and-purple clashing coat adorned with bells, and a lovingly drawn pair of hairy, knobby kneed legs with a pair of smart infantry boots. His groin was as meticulous as his legs, though somewhat exaggerated in size. The words "The Harlequin's Pantaloon" were printed below the obscene picture. Inside, a crowd was gathered around a sunken pit, screaming encouragement. Coins were being passed back and forth, mostly mundane ones.
Nereia separated from her retinue to arrange for accommodations, so Alice approached the pit. Inside, a Shadar-Kai and a Fire Genasi were brawling with everything they had. Both showed terrific bruises and the Genasi was even limping on a foot that was clearly broken. With a final twist, the Shadar-Kai threw the Genasi into the wall of the pit and proceeded to stomp on his head until something gave in. The crowd cheered, and the shadow elf preened. 
As the crowd passed their wagers back and forth, the winner demanded another challenger. Nereia appeared behind Alice, placing a meticulously manicured hand on her shoulder. "You should take him up on it."
"What? Mom, he just killed a guy!"
"I heard he enjoys fighting children," She offered, "He likes it when they squeal from broken bones."
Alice was stunned. "What do you care?"
"I just put six soul coins against her soul," Nereia answered, pointing at a Shadar-Kai woman using two nearly nude men as a throne with four more arranged around her on leashes. "I don't care for other children, but I know you do and I need that soul. Get in there and make me proud."
"How do I know you're- OH!" Alice cried out as her mother shoved her over the side of the pit. Six feet down, she landed on soft, ashy sand. Standing up with indignation, she was about to shout at her mother but was interrupted by the Shadar-Kai gladiator.
"A kid? Been forever since I twisted a kid in half. Gonna put your skull with the others!"
The eleven year old Tiefling rolled her eyes to her mother as if to say 'just this once,' and then raised her fists in a fighting stance.