Thwack 

Eyeing the man and children suspiciously, Thwack does his best to not draw attention to Peri and himself while he moves closer. 

Insight 5

Peri's Initiative: 6

Boko initiative: 16

Gerrard may act first. Four yellow baboon things have broken through his blast of air, and barrel toward him.

Gerrard:

Drawing his rapier, Gerrard executes a fancy maneuver and switches places with Qivys, bringing him closer to Boko to protect her.  He then moves straight into the group of baboons, facing the one in front of the door and keeping the wind fan blowing directly at it so it will hopefully force it and the two on the stairs behind it back into the building.  The young noble then slashes with two lightning-fast jabs at the baboon on his left, hoping to keep its attention on him and away from the vulnerable townsfolk.

(Using Bait and Switch to get a bonus to his AC, then moving forward so he is engaging all four baboons--basically two squares left of his current position on the map.  With any luck he will jam up the last two from exiting the building and joining the fight.)

Bonus to AC:  5

Rapier Attack 1:  Attack: 25 Damage: 12

Rapier Attack 2:  Attack: 10 Damage: 8

(Wind Fan is DC 13 Strength and currently aimed down the stairs and at the central baboon outside the building and the two on the stairs inside).

Before Qivys acts, he will see if these creatures are vicious and attacking for the sake of attacking or are they just reacting because Gerrard, Boko, & Qivys are standing in the way/in the path to their freedom. 
Insight: 3

These creatures, while similar in some ways to terrestrial baboons, seem unearthly, unnatural, and savage. They leap out of the doorway with unnatural speed, ready to tear apart anything in their path, their bright yellow hair blasted back by Gerrard's wind.

Gerrard's second swing bites one of the things on its arm; the wound bubbles with black, foaming blood.
His fan continues to blast a torrent of air at the baboons bounding up the stairs.

Three of them leap onto Gerrard in a reckless frenzy.

#1 Bite Attack: 24. Hit: 10 piercing damage.
#1 Fist Attack #2: 22. Hit: 5 bludgeoning damage.
#1 Fist Attack #1:24. Hit:5 bludgeoning damage.

#2 Bite Attack: 14. Hit: 5 piercing damage.
#2 Fist Attack #2: 25. Hit: 6 bludgeoning damage.
#2 Fist Attack #1:20. Hit:8 bludgeoning damage.

#3 Bite Attack: 14. Hit: 5 piercing damage.
#3 Fist Attack #2: 20. Hit: 8 bludgeoning damage.
#3 Fist Attack #1:19. Hit:4 bludgeoning damage.

The fourth fights back the wind, as do the two bounding up the stairs behind:
DC13 Strength saves: 7, 15, 22

The creature immediately in front of Gerrard is blown back by the fan as it leaps into the air. But two more take its place.

#5 Bite Attack: 24 Hit: 6 piercing damage.
#5 Fist Attack #1: 14 Hit: 7 bludgeoning damage.
#5 Fist Attack #2: 24 Hit: 7  bludgeoning damage.

#6 Bite Attack: 26 Hit: 9 piercing damage.
#6 Fist Attack #1: 14 Hit: 8 bludgeoning damage.
#6 Fist Attack #2: 16 Hit: 8 bludgeoning damage.

He can hear their alien, shrieking telepathic snarls in his head. "𐚄𐚅𐚆𐚇𐚈𐚉𐚊𐚋𐚌𐚍!!"

(One bite is to Gerrard's neck. Crit damage: +6 )

As Gerrard finds himself nearly surrounded by biting, snarling, thrashing alien simians, Thwack tries to sort out what's going on with coughing old man and the children. Unfortunately, as he tries to evaluate the situation, another blast of yellow, eye-watering vapor jets out of the building and he can see very little at the moment. Thwack and Peri can hear increasing sounds of apelike shrieks and fighting on the other side of the building.

Everyone but Gerrard may act. All attack rolls against the frenzied creatures are at Advantage due to their savage recklessness.

Gerrard:

Fighting off the frenzied attacks as adeptly as possible, Gerrard, tries to minimize the damage of the first one that hits.

Reaction to Parry:  9

"Let's see if'n we can slow this lot down a bit." Qivys says.
1st Action:
Qivys throws a bit of sand towards the baboons, casting Sleep at 5th level.
Spell Dice: 61

2nd action: 
Qivys moves up to Gerrard and places his hand on Gerrard's arm, healing him for 20 h.p.

Thwack 

Torn between returning to the front of the building to investigate the screams and completing his assigned task of searching the rear Thwack decides to continue on his current task. Bernard would call for help he justifies to himself.

With watery eyes he tries to see further into the cloud of noxious gas. He moves towards the last known location of the man. "Hello? We help you if you not bad guy!" He creeps forward slowly, waiting for a response.

Two of the foul, arcane baboons piling on Gerrard collapse, unconscious. And upon Qivys' touch, Gerrard's wounds fully heal.

The old man doesn't respond to Thwack's entreaties, as he seems overcome with a coughing fit. But the kids do. "This gas!" one cries. "Help us get him out of here!"

Boko and Peri may act. 

Peri:

Peri is also caught between backing Thwack up and going to investigate the commotion at the front of the building. He decides the other three can handle themselves well enough against a few cultists, especially with the militia on hand, so he hurries to the coughing old man. The kids seem to think he's okay, so Peri reasons he can't be too bad. He summons his Astral arms and wraps them around the old man, lifting him from the ground and dashing south along the canal toward fresh air. 

((BA: 1 Ki point to Summon Arms of the Astral Self -- Use WIS checks for STR checks.  Action: Dash for 100' total movement. I'll roll a WIS check in case it affects how far/fast I can carry this guy: 10))

Boko stares at the sky too long, and then thrusts a hand to the air, grabs something, and pulls down. A storm swirls out of nowhere and lightning flashes into the mob of monsters. (26 lightning damage on a failed DEX 17 save) Then she shifts into blue-tinged polar bear, roars, and tears into the fray, next to Gerrard.

Peri lifts the old man with his astral arms, and pushing through the crowd of concerned children, races south along the filthy waterfront past crates and barrels and derelict equipment, well outside the clouds of billowing vapor.

Boko calls down a bolt of arcane lightning from the grey skies. It explodes in a blinding flash near the doorway, next to two of the non-sleeping simian horrors. (I presume Boko would keep it away from Gerrard and the sleeping ones?)

Dex saves: 
#5: DC17 Dex Save: 24
#2: DC17 Dex Save: 8
 

Both creatures are struck, one worse than the other, but some of the power of the lightning seems to roll off their hideous yellow fur.  (Damage Resistance: Lightning)

Thwack and Gerrard may act next. (All attack rolls against the frenzied creatures are at Advantage due to their savage recklessness toward Gerrard.)

Gerrard:

Dropping his wind fan for the moment, Gerrard draws his dagger and erupts into a flurry of attacks at the remaining active simians (avoiding those asleep), starting with the most wounded ones!

Elegant Noble’s Rapier:  Attack: 14 Damage: 9

Elegant Noble’s Rapier:  Attack: 24 Damage: 9

Magic Dagger:  Attack: 28 Damage: 8

(Action Surge)

Elegant Noble’s Rapier:  Attack: 26 Damage: 12

Elegant Noble’s Rapier:  Attack: 23 Damage: 8

Thwack 

Before Thwack gets a response a tiny blur streaks past him and the man seems to float out of the stinking mist. "Terry, did you see..." His sentence cut short as he realises Peri has disappeared. Now concerned for his friend he moves closer to the kids. "You see little man around here?" he coughs at the kids. "Come, we move to fresh place" he beckons to the children and starts to back out of the cloud. 

It doesn't take much convincing for Thwack to lead the kids away from the building and toward the docks. "What happened? What is that yellow smoke? Where's Papa Coppercoins?"

Thwack can see Peri and the old man, one dock away, maybe fifty feet to the south. 

--

Meanwhile, Gerrard focuses on the demonic baboon on his left (#2) that had just been directly hit by Boko's lightning strike. It takes three powerful swings, but he finally manages to slay the frenzied beast.

Turning next to the one on his right (the one he had previously struck) he manages to get in two more powerful blows. It is nearly slain, but continues its attack unabated.

The shrieking, unearthly baboons continue to pounce upon Gerrard, at least the two still alive and awake; they are joined by a fourth that had been held back by the wind fan until now. (Two remain asleep.)

All vs. Gerrard:
#4 Bite Attack: 19. Hit: 10 piercing damage.
#4 Fist Attack #1: 23. Hit: 6 bludgeoning damage.
#4 Fist Attack #2: 23. Hit: 9 bludgeoning damage.

#5 Bite Attack: 22. Hit: 10 piercing damage.
#5 Fist Attack #1: 17. Hit: 6 bludgeoning damage.
#5 Fist Attack #2: 26. Hit: 9 bludgeoning damage.

#6 Bite Attack: 25. Hit: 9 piercing damage.
#6 Fist Attack #1: 11. Hit: 9 bludgeoning damage.
#6 Fist Attack #2: 25. Hit: 5 bludgeoning damage.

Everyone but Gerrard may act. All attack rolls against the frenzied creatures are at Advantage due to their savage recklessness.