Talion looks up the stairs then back down to check on Lucky, his own suspicions about the dog revived by Sho's clear distrust. "Good dog" he says tentatively and, perhaps, hopefully: Saving just one extra soul from this house of horrors would be a victory, and something that the cursed children would likely approve of.

He cautiously moves up the stairs, wary of lucky, and expecting the roof to collapse again at any moment.

(( Assuming initiative means we are in combat:
Move: Climb up, follow Sho.
Action: Dodge
Otherwise: just as described above))

At the mention of the smoke, Bertolt will move to pull his tunic up in an attempt to push through it easier.  Like the others he will continue to keep together and get towards the exit and leave the cursed place behind.

Okay each of you pulls yourself and otherwise help each other get up into the room.  There are a few changes since the last time you were here.....

As you pull yourself up out of the trapdoor, you notice several changes to the architecture of the room and, seemingly, the house itself.  First, the mists are gone.  Where it used to be dust-free, immaculate, and clean, it is now dirt-strewn and items are haphazardly strewn across the room.  All the windows are bricked up and the fireplace is emitting a noxious black, yellow, and green cloud - your vision is heavily obscured.  In spite of this,  your eyes are drawn through the cloud of gases to the doorway, which has been replaced by whirring and slashing scythe blades!  You can just make it out visually but you hear it easily...Looking at the interior walls, you note they are cracked and splitting and otherwise looking very weak.

1. Erven, Onyx
2. Bertolt
3. Sho, Talion, Lucky Bear

Erven and Onyx, you're up!

MAP (grey stars are scythe blades, the cloudy stuff is the poison)

Erven doesn’t like the look of the blades.  Seeing the cracked, weakened walls, he would try to run and bust through the wall closest to the front door, the way out!

Onyx notices Erven move to the wall, and despite the heavy obscurement, can probably guess what he's trying to do.

Sensing the damage to the wall, Onyx raises his shield and attempts to bulldoze through his own section.

Athletics (if applicable) 6

Okay, first, both please make a constitution saving throw.

Near the north western corner of this room, you notice a section of wooden wall that looks like a good candidate to smash through...
Erven, you can make a strength (athletics) check to try to break throw the wall....
Onyx, you run towards the wall but are unable to get through completely.  You do, however, hear chittering and squeaks as you smash the wall...

Bertolt you'll be up next!

NOTE: on your turn, you'll first roll a constitution saving throw.

Erven con saving throw :  13 

Erven Athletics check to bust through the wall :  5 

Con Save: 19

Bertolt not sure if he will be of much help will attempt to help break through the wall. (I am more trying to give advantage because his strength is +0...)

"Oof - hey, do you hear mice?"

Constitution 16

Talion Con Save: 21

Talion pulls the crowbar from the side of his pack and approaches the wall, flexing his arms, a look of concentration on his face as he casts a practiced eye over the wood, looking for weak spots. He ignores Bert's offer of help, "Help the priest, if needed."

Upon hearing Onyx's remark he wrinkles his nose. "Mice you say? More likely rats or bats..." He pauses wondering at the wisdom of breaking into vermine-infested walls, then glances at the blades and at Sho.

Resigned to whatever insult the house is going to send his way, he turns back to the wall and tries to break through it.

Athletics(adv): 17 (advantage either from crowbar or Bertolt)

(( If 17 is enough ))

He winks and grins at the other two, "Amateurs."

Talion - you are able to smash through the wall no problem, breaking down a 5-foot section.  As you wink and grin at the group, you see their eyes widen.  As you look back to your handiwork, you realize you have also unleashed a swarm of rats, which fall into you!  Gnashing teeth and sharp claws surround you!

Swarm initiative - 14  

Lucky Bear CON save - 6 

Sho is up!  Then Lucky Bear (depending on her CON save...)

MAP

Con Save: 4 

Quote from WhiteByakko >>

Con Save: 4 

 Sho, you pull yourself up and take in a big gulp of smoky air.  It tastes like apples - delicious!  You can feel the pieces in your mouth, so succulent....but then you feel them start to wriggle around in your mouth!  You spit into your hand and it's filled with squirming maggots!  You cough and retch, trying to get the critters out of your mouth, you feel them start to go down your throat, you cough more and more....and then it's over.
Take 3 psychic damage.

Still your turn Sho.

Sho continues to cough from the toxic gas, he opens the palm covering his mouth and he sees the squirming maggots, then he looks at it again he sees pink spit mixed with blood. He wipes it off and grimaces at the swarm of rats climbing onto Talion, he opens his mouth to tell him to get away but that got replaced by another series of coughs as well, and he just manages to complete his spell under his breath.

Sacred Flame at the rats: DC 13 Dex Save or 3 radiant

Quote from WhiteByakko >>

Sho continues to cough from the toxic gas, he opens the palm covering his mouth and he sees the squirming maggots, then he looks at it again he sees pink spit mixed with blood. He wipes it off and grimaces at the swarm of rats climbing onto Talion, he opens his mouth to tell him to get away but that got replaced by another series of coughs as well, and he just manages to complete his spell under his breath.

Sacred Flame at the rats: DC 13 Dex Save or 3 radiant

 As mentioned above, the area is heavily obscured with the noxious clouds...but you're able to see your comrades' shapes in the chaos and getting near them, you hear and feel the swooping scythe blades.  And from here you see something happening to Talion...it looks like rats.  You have to move 15 feet to get any type of sight on them.  
Dex save for swarm - 9 

Talion, also make a Dex save!  On a fail, take the same damage above.

Lucky Bear sniffs, then sneezes 6 times in rapid succession.  She sniffs her way over to Erven and will make a bit on the swarm (disadvantage) - Attack: 9 Damage: 5 

End of Round 1!
Round 2!

1. Erven, Onyx
2. Swarm, Bertolt
3. Sho, Talion, Lucky Bear

MAP 

Talion Dex:8

Edit: and a concentration check: 7

Erven moves forward to G3 and attacks the swarm that is on Talion.  He is using his rapier.  “Hold still, let me swat these rats off of you!”

Attack: 19 Damage: 8 

 "Ouch!" Talion flares glares at Sho. "Let me get clear before you do that again!"

(( Edited to fix typo ))

Constitution Saving Throw against the Poison Smoke: 13

Onyx focuses on the void in the wall, the rats swarming Talion.  Pale green mist begins to pour out of his gauntlets once more.

"Push through and get clear, Talion!"

(Ready Action: Cast Poison Spray at the Swarm once it no longer shares a square with Talion.  When and if it triggers, the swarm must make a DC 14 Constitution Saving throw or take 10 poison damage.)