“There are also some of them that point inwards,” remembers Tryn in response to Progo.

Goraseth points at the shield "Progo, this shield seems still in good shape. It could be useful for you". He then rejoins his camarades and looks silently to the dozen of ghouls waiting for them on the ground floor.
He turns towards the group and whispers: "Well this was a glorious fight, but I must say I have used all my tricks, divine spells and martial skills. Tryn looks also exhausted, and I am a bit skeptical on fighting such a group of undead. I was thinking of regrouping in the forest nearby, I don't they the undead would follow us. Then we come back fresh tomorrow."
After a pause, he looks once more through the arrowslits "I mean we could also snipe one or two of those undead from here before fleeing through the hole we use to climb here..."

Rayce takes position at one of the openings onto the court yard. She summons arcane power that crackles like lighting between her hands. If anyone is joining her she will start hurling eldritch blasts down.

16 to hit and 2 force +2 thunder damage=4

She will leave at the first sign of bigger trouble.

"I am eager to leave," she says "but this seems like too good an opportunity to take out those ghouls to pass up. I would much rather face them from here, than face to face."

When Tharanau sees Rayce target the monsters, he decides to join her and sends a ray of frost down below (24 to hit for 3 dmg and 10ft less movement). "Hopefully they're not all running around and up the stairs now.... worst case we all need to jump though the murder holes and hope they don't follow."

In that case , Goraseth will heal himself and place himself close to the way out, covering the retreat.

could he place one of the big cauldron in front of the strair to block the access?

Progo you do not see any traps, and proceed to take the shield which comes o you with ease.

Rayce and Tharanaus hits their target.

Goraseth you can move the cauldrons easy since they are on little carts, the cauldrons are full of dirty oil that is rather solid (you know not solid as a rock but jelly-like cold fat) You can get it out of the cart in front of stairs with someones help and block the way this way. (either choose which side you block or you can declare to block both sides)

Ghouls at this moment appear confused about the damage, but are looking around to seek its origin.

"Good call, Goraseth!" Tryn exclaims and helps Goraseth manoeuvre the cauldrons. "You think we could put this cold oil on the stairs? If they come up that way it will sure make it harder if not impossible. We'd still have to guard this tunnel of theirs. Or we could put a cauldron in front of that too? Perhaps, with a healthy application of grease to go with?"

I’d like to block both side for now. Does it look like the oil could be set on fire ? 
Tryn could help while the 3 others are sniping

Ooc: Rayce has the create bonfire cantrip. If the ghouls start up the stairs she can heat up the oil and set it on fire.

Next round: 14 to hit and 8+2=10 damage

Well, you can certainly try to set it on fire ;). Do mind that it will be super hard at it current state. if you would try to pour it out it wont, and even if it would then it would just blob out of cauldron. First it needs to be heated up. Either by getting it to the fireplaces at the sides of that room (with fireplaces first alit) or by create bonfire cantrip. It would need to be heated for at least a minute to be liquid and hot.

Second attack ray of frost 10 to hit for 6 dmg.

"Maybe we should stop the attacks and think about this plan first." Tharanau steps away from the slits. 

"Let's light the fireplaces and heat up the cauldrons. Is there three of them? Then we could prepare one for each of the stairs and one for the tunnel?"

"Yeah, I like that idea. We could use the fire and cook some of the spiders, too, and throw bits and pieces on the stairs, and open the doors downstairs. When they all come for the feast, we will be ready to pour hot oil onto them!" 

Tryn follows the others with shooting at the ghouls. Only his shooting is a bit different. He shoots ideas and images into their heads. One of his favourites is to make a ghoul's arms appear - in their mind only - as a bone with fresh meat on it. Let's see if they start gnawing... cast Mind Sliver for 2 psychic damage unless succeed in INT ST DC 12

"Good idea!"

Rayce will use her cantrip and start heating up one of the cauldrons, maintaining concentration on it. Then she will return to the arrow slits to continue firing.

"Progo's arrow count is starting to get a little low. Progo will keep them until a more pressing  dangerous situation." 

As plays with his new shield trying to get adjusted to carring it around.

One of the ghouls that was previously hit by rayce is now starting to chomping on his own limbs. (consider him beaten - damaged reduced him to 0)

The one who was shot byt tharanau is still confused and is not yet aware of your location.

One of the caludrons is getting heated. Is anyone else trying to do the others? you can use firewood from fireplaces and some tinderbox to start on the other two? who does that and does anyone do anything about spider carcasses?

"To bad Progo couldn't serve undead the spiders, that were marinated in grease, and then set that on fire."

“Why not?” Tryn begins to cut off one of the giant spider’s legs and tries to force it through an arrow slit. “Let’s first see if they are interested at all in spider meat, first,” he comments to Progo explaining his cause of action.

there is a response. five of the ghouls jump on the leg and gobble on it. It does not last long there. Even the one sob bastard ghoul that bit off his own legs and arms is trying to get to that. but unfortunately for him he can not reach it.

Goraseth sees his camarades doing a great job at sniping the ghouls from afar "Great idea...keep at it, less ghouls to fight in melee to better it is !"