(Not sure if my turn but if so, Goraseth will light up a torch and ignite the oil in the stairs and the ghoul with it ! (I’m guessing it is my action)

”let’s clean this place with fire !”

The oil on the left is effectively set on fire. ghouls are getting fried but still advance, first one slashes with his claws at Goraseth and meets his shield.

On the right ghoul attacks Tryncaryn but without succes, and you see there are another 2 coming from downstairs.

Tharanu, due to the fact that the ghoul you are fighting with was prone and had to stand up he does not reach you yet. there is also another who came up from the tunnel. You can not hear past the wailing of these two whether there is more incoming.

"Uh... There are two more coming up this side!" Tryn shouts out. "I guess I have to stay here and block them. Might be we have to retreat if it gets too much for one of us to deal with." He brandishes his quarterstaff and sinks it into the ghouls tummy before aiming his knee at the ghoul's chin. 

Action: 19 hit for 4 damage
Bonus: 21 hit for 5 damage

Tharanau activates the witch bolt again on the connected ghoul (dmg 8). He then tries to see how the second ghoul did with the oil and if it slipped. 

"Tryn, I am fighting one and one more is coming through the tunnel. All good so far, I think I can take them!"

Tryn your attacks are successful. Tharanau ghoul still barely stands after your damage, and second ghoul did not slipped.

Progo stepping into the webbed area without realizing that's where he was backing into "blast!"

Well tye webbing gave him a good sticky set for his feet to take a shot:

BA Steady Aim 

Attack: 23 Damage: 14 with sneak 

That was aimed at the one in front of Goraseth 

your arrow plunges into ghouls head and is now sticking out of both sides of his head, that throws him a little of balance but does not destroys him yet.

In that case, Goraseth will try to push the almost dead ghoul onto the next ghoul in line
Athletics: 9

"Three ghouls on me here !" He shouts at his compagnons

Rayce will move to C10 and fire an eldritch blast at the ghoul in front of Goraseth.

9 to hit, misses in the midst of fighting and confusion.

She then moves back up to E10.

She maintains concentration in the fire under the ghoul in front of Tryn. 2 damage if they fail dex dc 14.

Goraseth you successfully push ghoul onto the stairs(he rolled 8), and he tumbles down rolling on flaming oil and ending his journey hitting the empty cauldron at the bottom of the stairs with a loud crack, that is his head that fallen apart after that encounter with the cauldron - it is defeated.

One of the ghouls on left stairs slipped and tumbled down. One came up but is still on stairs, one managed to get close to Goraseth and attack him, but he did not pierced the armor with his claws yet. There is no light in the chamber below, but from what light leaks there Goraseth can estimate there are maybe 3 or 5 ghouls downstairs trying to climb the stairs.

On the right. Ghoul that is in front of Tryncaryn attacks him (16attack) and deals 4 slashing dmg. Tryn should make DC 10 Con save or be paralyzed for 1 minute (save can be done again on each turn of being paralyzed). one another is climbing up and one of them who also tried tumbled down after slipping. Tryn can estimate there is around 2 or 4 of other ghouls downstairs.

Tharanau is attacked by the ghoul who that have witchbolt on him for (attack 15) 7 damage Tharanau should make DC 10 Con save or be paralyzed for 1 minute (save can be done again on each turn of being paralyzed). The ghoul who was further away slipped on oil, but stood up and is closing on Tharanau.

Tryn glanced downstairs to appreciate their predicament but the ghoul took advantage of his momentary distraction and buried his claws in Tryn’s arm (Con save 8). Tryn pulled back instinctively and wanted to assume a defensive position but his body felt sluggish and soon stopped following his instructions altogether. The bloody ghouls must have poisoned him! Wide eyed he fought the effect of the poison and he finally managed to shake free from it (Con save 12) before the ghoul could profit from the situation. „There are at least a handful of them still trying to get up on this side. I’m not sure if we can hold them back. This one almost got me good,“ he squeaks.

(I believe the roll in his turn is at the end, right? If not, Tryn will dodge this turn.)

Tharanau hears Tryn scream and sees him freeze for a moment. This fraction of a second is abused by the ghoul who slashes into Tharanau's leg. Tharanau can feel the poison, can feel cold, the emptiness rise inside him (CON save 6)... he is unable to move and loses concentration on his witch bolt (CON save 6). He does however not give up this inner fight, suddenly seeing his children, remembering their smiles one by one and can feel the control of his body return to him (end of turn CON save 19).

"We need to get out of here, if they paralyse us all, we're done for!"

EDIT (oooops, I forgot I had shield - if allowed, I would cast shield and avoid the attack of the ghoul... then I would like to disengage and maybe as a bonus action close the door to the room with the tunnel) and walk as close to the slits in the ground as possible to prepare our escape)

yes tryn it is on the end of turn. 

yes tharanau you can shield up. You have no key for the lock so doors can be just regularly closed as a free action. but that wont stop them to reopen them again of course.

Goraseth’s old gladiator habits resurface with the danger of death. The odds of this fight were not looking good.

“Progo, Rayce ! We need to move, this is too much and I can hear more downstairs making their way up. We need to help Tryn. Shoot the ghoul on him ! Tharanau be ready to retreat”

(waiting to see what Progo and Rayce are doing, I might take dodge action and try to join Tryn)

Seeing how everyone is getting ready to leave, Tryn reflects on the situation with his mind eye and sees how one ghoul clearly misses his mark (he’s using his last foretelling roll on the next ghoul attack that he can see. The roll will be considered a 3).

Tharanau hears Tryn scream and sees him freeze for a moment. From the corner of his eye he sees the ghoul move - and is sure that their claws are going to bury deep into his leg. With a swift movement Tharanau is able to cast shield and avoid the attack. He breathes for a split second, then attacks with his witch bolt that is still connected to the ghoul (dmg 9). 
Tharanau then retreats into the main room and closes the door to the side room. Retreating as close to their escape rope as possible.

"We need to get out of here, if they paralyse us all, we're done for!"

Progo push on through the webs (BA cunning action Dash)until he reaches D10 or C10 ( which ever is a clean shot at the on next to Tryn).

"Progo says it's time to go, I don't think they will know to stop at the window, hopefully the fall does most of our work!"

He shoots at the one attacking Tryn:

Attack: 18 Damage: 14 with sneak

Rayce moves to d11 and throws her dagger at the ghoul

23 to hit and 7+2wrath+1 sneak=10 damage.

Then she will head straight for the rope.

The ghoul is still standing in her bonfire and in the oil fire.

In that case... Goraseth will disengage and moves to E10, hoping that everybody can make it to the ropes