The Valley of Ends

Immediately beyond the hidden door, the winged cat finds three cloaked figures laid out against the sides of the tunnel that goes farther down, curving around out of sight. 

Del sighs and goes to the chest. He cuts the rope, and attempts to drag it out of the cave

As Del cut the rope, he can see whatever tension the rope disappear and he drag a relatively light chest out of the cave. Taking a deep breath, he pops it up to find the other end of the rope tied to the roof of the chest and nothing else inside the black painted chest. 

Do the figures in the hall react at the appearance of Sabastian? Does the cat see any way to open the door from this side? Is there any reaction on this side of the door once the rope was cut?

is cat invisible? He doesn't see anything that says opens  door and rope seem to have no effect on this side of the door.

Onyx is to slow to stop Del and can only watch how the rope is cut. He jumps backward in expectation of a massiv trap. But once nothing happens he keeps on watching Del in amazement.

Del shrugs. “I don’t think it’s a good idea to be here too long. We need to act, quickly.”

Can I investigate the rope? 4

Onyx shrugs his shoulders: ”We already rested for 8 hours and I still think this here is less dangerous and whatever is in the center.” 

“I mean in this realm. It’s clearly not meant for mortals.”

Why would the cat be invisible? Nothing was done to make him so, so not sure why it is even a question... Regardless, Sabastian was not invisible when Gotch sent him to the other side of the door, so my previous question still stand... What happens when the cat appears there and when the rope is cut. Gotch would have readied an action to simply send his familiar to its sanctum if anything reacts to its presence.

Del's cutting of the rope didn't leave too much rope sticking out of the wall where there's just a small hole, just slightly bigger then the rope within the hole. Onyx finds it's a normal hemp rope, not too different from one he has. A few experiment light tugs Onyx find there's something springy on other end of the rope.

Salys calls out to the others, "Are we done exploring this nonsensical realm? Can we get back to trying to leave now, please?"

Resfaen is startled out of her mutterings and looks around wildly at the shout from Salys.

(Two seems to be too many familiars to keep track of. It was other familar who could turn invisible) 

The Treesym looks around the three figures start to stir. A hair raising, sharp pain almost immediately envelopes everyone within the cave. everyone inside the cave take 3 instance of 5 necrotic damage. Del has moved out carrying the empty case. The figures start clawing at the back of the door as wailing emits from them. The winged cat can make out almost scream like faces of gray pale skin before it's hit by the necrotic . 

What doies everyone do?

Del pauses with the box and shoved it back into the cave with his foot.

Onyx will try to leave the cave, no point in staying in the area that hurts you.

Onyx has to jump in his haste out as the chest comes rolling in from Del's kicking of it.

(I assume Gotch used his reaction to send the familiar to the extradimensional space, as that was his stated action if the cat saw anythign that was dangerous. Gotch would have considered the figures dangerous as soon as they started to move and thus would have used his reaction, readied action, to send the cat away.

Upon taking some necrotic damage himself, Gotch will move to exit the caves.

Seeing the others come rushing out of the cave, Salys backs up and readies his weapons, "What is it? What happened?"

The majority of the party watch as Gotch and Onyx rush out of the cave, marking of dark necrotic damage on their body that fades after a moment. Gotch explains what he saw in the tunnel as he looks at the hidden entrance where the party could swear to hear the scratching from this distance.

(Arcana or Religion check to determine what the creatures were if you want)