"Not my friends!"  Delph says, the fiery little Fairy leaping to action suddenly.  He speeds into the middle of the oozing blobs and summons his Astral Arms, the ghostly arms whipping through the air suddenly in all directions.  Ooze splatters everywhere as the arms pummel the slime boiling in the corner as well as the blobs that are pursuing the rest of the band.  Delph then takes a moment to line themself up and drop a huge fist on the big blob fighting Ralik, smashing it hard against the ground.  

When Dageron shouts fire, the people in the library begin to stir around, some of them looking at one another, and talking in hushed whispers.  The lady at the desk comes walking down the aisle toward Dageron quickly as she tries to figure out what's happening.  

"Fire?  What's on fire?  Stay calm everyone and please proceed outside.  Remember to walk, not run!"  

The Barlgura obeys Johnathan’s command and begins to tear into the slime creature near Shavaris, first with a bite attack followed by 2 fists slamming down on what remains. The creature seems to be attacking aggressively as it leaves itself open to counterattacks.

(Creature went reckless, all attacks are made at advantage on the creature for one round)

Action: Multi attack
Bite: To hit, 15. Damage, 13.

Fist: To hit, 16. Damage, 8.

Fist: To hit, 24. Damage, 12.

Travin in his black and gothic illusory disguise, isn't rebuffed so easily by the girl who seems to want to pay no more attention to him. He swoops around and takes a book from the shelves that seems to call out to him. 

A book about gargoyles and grotesques, authored and annotated by Stephen King... He opens it and takes a read, leaning against the bookshelf next to the girl. 

"people in the city rarely look up, they don't see...them," he said, gesturing to the horror across the street, the horror so strikingly at odds with the anonymous building from which it sprang, like a tumor sprouting from the mild brow of some harmless middle-aged and middle-class executive. "But they...well, you'll notice that they're almost always looking down." He paused, then smiled again. The smile was different this time: thoughtful, and, I think, the tiniest bit uncomfortable.

"We don't see them," he said, "but they see us." 

Travin thinks for a moment and withdraws any attempts of getting the girl's attention. "Hey sorry for bothering you, though if it's any consolation nothing in this world is real" he casts back as he walks off to a table to investigate the book more thoroughly.

The attack from the blob came quicker than expected. A pain on the side of his head with a flash of white, followed by intense ringing in his ears woke up something primal in him. 
Ralik retaliates with cold precision as he jabs the daggers three times in rapid succession, still his ears ring.
He creates distance from the demon that seemed to come out of nowhere, but stays within reach of the blob. His ears still ring. 

"IT HIT ME HARD! I CAN'T HEAR!" Ralik shouts excessively loud. He glances to his teammates for any sign of acknowledgement.

 He hears nothing but a high whine as the battle unfolds.

Rolls:

Johnathan looks over to Ralik as he calls for aid. Johnathan sends healing light to close some of his wounds as he shoots eldritch beams at the slime attacking him.

Bonus Action: Healing light, Ralik heals for 8

Action: Eldritch blast

Beam 1: To hit 19. Damage 15

Beam 2: To hit 13. Damage 7

Echo continues to look for the others, shouting in Johnathan’s voice. Dawn Guard, we need you back with us. There’s a fight going on. 

With the crit the creature takes an additional 5

Adam continues to run toward the sound, he finally sees them fighting the slime and he pulls out his lightsaber, but uses the rest of his action to dash to get into melee.  “What the hell is going on?  What is the plan here … are we getting out of here or what?  Did you find what you need?”

Dageron, on Adam's heels, says, "We have been found, and if the enemy is consistent, then Human authorities are coming as well. We should withdraw - we cannot destroy that slime without causing incalculable damage to this place." He moves between the Ghostbusters and the enemy, his shield raised. His free hand points to the mass as he yells, "Golfeki!"

(( Attacks 1&2 are Sacred Flame. The slime thing gets a DC 13 Dex save for each attack. Attack 1 = 7 radiant damage, Attack 2 = 12 radiant damage ))

Ralik's daggers slice pieces of the slime off in the split second before Johnathan's Eldritch Blasts finish the job.  The first blast hits the slime attacking Ralik and disintegrates it.  As it crumples, the second beam passes through the air where it had previously been and slams the second, smaller ooze after the Hexblade, destroying it as well.  

Dageron's attack on the surviving ooze destroys it outright, scattering it in evaporating sheets across the floor.  

However.  

The slime bubbling in the corner has been very busy.  The building shakes as huge chains dig into the ceiling, into the walls, while bones, somehow pushed up through the rupturing hole in the floor, begin to take on a sort of segmented tripod design beneath the thing.  The slime molds with the viscera it has dragged up with it, and belts of sinew begin to swing up and around as it starts strapping itself together in something more or less spherical...though terribly imperfect.  

Eyes open all over the thing...eyes, and mouths...and sometimes eyes inside of mouths.  It's covered in teeth.  The mouths sport all sorts of teeth, in fact; some humanlike, some fanged and sharp.  Not only the mouths are covered in teeth.  Some sections of the thing have random toothed growths sprouting from them.  Teeth...and hair.  

It slowly turns, one gigantic main eye that is actually a cluster of much smaller eyeballs, a sort of giant compound eye, turns on the Dawn Guard and the Ghostbusters, and each small eye begins to blink slowly and rapidly.  

Gore and puss drool out of the thing everywhere, splatting the floor in heaps.  Some of the heaps begin to move as they fuse with the pink slime all over the floor.  A smell fills the room like rotting flesh.  It's absolutely sickening and strong enough to be disorienting.  The air begins to grow heavy with a green fog of filth.  

One of the mouths in the center of the thing opens, and a very familiar voice to everyone but Dageron cries out.  

"Dawn Guard!  Help me!"  It says, bright, loud, and feminine.  "Help me!  Help me help me help meeee!"  

The voice distorts as it sceams the baleful cry, but the next voice is uses isn't the same.  It's full of hatred, malice, mockery, and decidedly masculine.  

"I see you."  It says with a chuckle. 

Behind them, on the steps to the basement, the Librarian, having followed Dageron, stands in wide eyed shock.  

"What the f*&% is going on down here?"  

Shavaris instinctively jumps backwards at the sight of the abomination in front of them.  Hoping, but doubting that the chains will keep it in place, she shouts to the GB and the stupid librarian, "Get out of here!  Move move move!!"

Calling forth Eloise, Shavaris has her sister appear directly next to the creature.  The voice of the thing grating in her mind as she tries to place the familiar voice... 

Shavaris throws forth her scimitars, Sick and Twisted, taking care not to hit a chain.  

Attack: 13 Damage: 12

Attack: 14 Damage: Unable to parse dice roll.

sneak attack damage due to Eloise being next to it: 14

Using her action surge, she sends Sick spinning again to slice the monster..

Attack: 31 Damage: 13

And Eloise uses her Unleashing Incarnation to attack the creature as well...

Attack: 30 Damage: 8

Shavaris then starts backing up towards the exit.

Eloise dissipates as soon as she appears next to the creature, her body fading in, then blown away like fog in the wind.  She isn't even there long enough for the creature to register her presence.  

The creeping miasma of the creatures very presence engulfs Ralik and Shavaris, with the Wood Elf feeling the immediate effects.  Before she has time to cough the miasma out of her lungs, the thing's many eyes land on her and flashing waves of yellow-pink magic ripple through the air, washing over her.  Disoriented from the initial damage, there is no chance for her to avoid this attack.  It's immediately apparent that Shavaris is in deadly trouble.  

"The flesh is weak."  The creature says as it moves forward, semi-floating, semi pulling itself along with the chains extending from its body as it tears at the ceiling above them.  The puss and gore and ooze drooling from the thing's body begins to move on the floor.  

The Ghostbusters don't need anymore incentive.  They haul ass toward the stairs, with Zeddemore pushing the Librarian back out the door.  

"THAT IS DEFINITELY A CLASS 8 FLOATING REALLY BAD THING!"  Stantz screams. 

Shavaris inhales the poison and feels the magic wash over her.  Her body doesn't feel right anymore, almost malleable as she tries to stand there.  She leans against a wall and whispers, "Adam..." looking around with just her eyes as her head is also resting against the wall.

Dageron, staying as far back as he can while maintaining line of sight, yells "Golfeki!" twice more. This time the radiant light exploding on the target is significantly increased (Guiding Bolt, twice - attack 1 = 12 to hit, 13 to damage, attack 2 = 13 to hit, 16 to damage )). He yells to Adam, "We cannot approach it. Can you use the Force to pull the others away? If not, we may have to use rope to lasso them towards us. We must act quickly or they will both be lost, and then we must retreat!" 

The floating horror turns its gaze on Dageron when he attacks it, even when the two Guiding Bolts burst uselessly against its hide.  As all its many eyes land on him, blinking in unsynchronized chaos, they begin to flash a puke green pattern...

Delphinium perks up, watching the situation go from bad to really, really bad.  They fret for moment, trying to figure out how to attack this floating chained blob of nasty before their eyes land on the Ghostbusters, still scrambling like dummies as they try go get out of the basement.  

"Oh!"  The little Fairy shouts, the brief disappointment of not being able to punch this thing lifted.  "Hold on!  I'll save you!"  

Delph zips through the basement and grabs two of them, Zeddemore and Stantz, before shooting up the steps toward the librarian who was still indignantly asking what they were doing.  

"Look out lady!  Fairy coming through!"  

Travin hears the wood break several levels below him and begins hearing talk of a fire, try as he might to ignore the disturbance he sighs for a moment and heavily considers returning to the book, before packing it away and beginning to walk down the stairs.

Travin keeps an eye out for a small red box on the wall as he goes. Debating with himself whether it is better to evacuate the building of the civilians whilst almost certainly bringing emergency services to the library. After a moments internal debate he stops looking for the little red boxes, these people in danger weren't real after all, but their actions had consequences, their guns could still kill...

 The ground breaks before him and slows his path to the group.

Johnathan sees Shavaris as she gets hit from the goo. She doesn’t seem to be moving that much. He looks at the demon. Demon, grab Shavaris and bring her to the exit. As he says this he points at Shavaris to let the Barlgura know which humanoid he means. With the command the demon pushes past the goo creature (it is open to an attack of opportunity), grabs the humanoid and starts making its way to the exit. After its movement Johnathan holds his head as he seems to be whispering something, though not very loudly. It causes him to lose focus for a moment, but it’s enough that the demon is released from his control with a crazed look in his eyes and roars a primal scream. RRRRRAAAAAAAAA

Johnathan recovers and lifts his head, realising what just happened. Oh crap…

Action: Grab Shavaris,

Movement: 40 feet

The creature's many eyes shift from the Dawn Guard to the Barlgura as it registers what just happened.  Then it speaks a one word command to the lesser fiend.  

"Attack." 

The Barlgura ignores its new would-be master as Ralik interrupts the command. 

Meanwhile the chains continue to tear at the ceiling...

Coughing, Ralik quickly views the battlefield. He sees the thing's moving mouth and concentration. Ralik reaches out and swipes at the air with a dagger, severing the weave the monster was controlling, causing its magical command to fail.

The poison from the thing burned his insides, but he grits his teeth and moves to Shavaris. He places a hand on her shoulder and points to the sky with his other dagger then looks to the exit. They both teleport as far as his 90ft limit allows, appearing there with a thunder clap that Ralik cannot hear. He makes sure not to appear close to any of his allies, in order not damage them. He his best to pull Shavaris along in an attempt to escape . 

Johnathan gives a concerned look as he realises Shavaris was in big trouble with the demon now. He tries to think of a plan to get her out of there when he sees Ralik teleport her away. He sighs of relief a little before addressing the others. This is bad, the demon is loose. Don’t go near it, it will attack the closest thing. With that Johnathan starts moving towards the exit. As he does so he aims his eldritch beams at the goo that seems to be trying to command his demon. 

While this is going on Echo starts flying towards the exit outside.

Action: Eldritch blast on goo.

Beam 1: to hit 27. Damage 15

Beam 2: to hit 14. Damage 12

Movement 30 feet to exit