Kass blinks, and sits up. "I feel... Better, I think. You all look okay, too. That mook was a real piece of work. Glad we pulled through that scrape, as touch and go as it was. Where's the nearest pub?" 

Well, the nearest pub would be the Yawning Portal tavern, which is abouit 23 levels of dungeon above you. Thankfully, you killed most of the monsters on the way down here.

Wripers yawns and stretches. He's about ready for a nap, the poor little bone-crusher.

Amari chuckles at Kass's quip about finding a pub. She then says, "A bit of a rest, maybe? I don't have much spellcasting capability until we do so."

In post #240, I said everyone gained the benefits of a long rest, so you get all your stuff back.

You look around, refreshed, and come to the logical conclusion you should leave the dungeon. After all, you have freed the place from the rulership of the Rune Masters, which is the whole reason you started an adventuring career. You get vibes akin to finishing an open world zelda game, and you beat the final boss but you can still play the game, and you're like "well what do I do now?". That may seem like a very specific feeling, but it is one I have personally experienced many a time.

"It may be worth heading topside and telling Durnan that the area is secure, at least for now.  Happy to follow along on any other misadventures, though."  

Wripers finds himself curious about what else may lie in this room. He begins sniffing about, as always. Hopefully, he doesn't eat any treasure he finds. Again.

[Perception: 23]

Amari joins Wripers in the effort to find anything of interest in the room, but she opts for a slighty more nuanced approach.

Ruin simply follows the others... he is a warrior, after all. It is his duty to protect his comrades.

Wripers and Amari search the room, but find nothing. Nothing at all. Though when Amari looks at the door that leads out of here, the presence of necromancy magic is almost overwhelming.

Do you leave the final chamber?

Kass learns from Amari about the necromantic magic infusing the doorway, and doesn't want to deal with that kind of headache... So taking a cue from a little voice inside his head, he'll cast Dispel Magic at 9th level, because of how far down the group is and the nature of the challenges thus far. 

To be clear, the necromancy is not about the doorway. It is beyond the doorway. Keep that in mind,

Ah, okay. Kass will step out of the chamber, carefully, until he can identify the source of said necromancy. 

Amari bows her head and turns her mental focus on the area beyond the doorway, trying to discern the presence of any undead...

Eyes of the Grave (XGtE, pg. 20)

As an action, you know the location of any undead within 60 ft. of you that isn’t behind total cover and that isn’t protected from divination magic until the end of your next turn. You can use this feature 6 time(s) per long rest.

As Kass pushes the door open with a creak, Amari, whose eyes are glowing intensely, follows close behind. While Amari does not see any undead, the atmosphere of the place is strangely different. The stench of rotten flesh fills the air, and ash drifts along, landing lightly on top of your heads like twisted snow. You walk through the antechamber, the strange mirror in the corner now shattered upon the floor, and push open the doors to the wider dungeon. A long flight of stairs lead down into the darkness, and those of you with dark-vision see that the walls are splattered with blood and gore. An uneasy chill fills the air, and you gag on the horrible smell which wafts towards you from the passage beyond

What do you do?

Do you head down the stairs?

Amari casts invisibility on herself and begins the descent...

As you descend down the steps, your form invisible even to those with nightvision, the things you noticed earlier: the ash, the stench, the overall chilly feeling growing stronger and more noticeable. Finally, you come out to a set of double doors, which presumably you push open quietly, since you hear no noises on the other side of the door. 

Stepping into the chamber, you look around, and you feel as though you've been here before. But you can't quite place where. Weird. What are you even doing here? you shake your head and continue surveying the chamber. In total there are seven sets of double , six sets set into the walls at regular intervals, and you entered from the southernmost door. the east, instead of a double door, is a passage that when you peer down it, leads off into two branching tunnels, one heading north and the other heading south.

What do you do?

Kass starts looking around for anything that might identify where the doorways or the passage way lead.  Signs, carvings, footsteps, any clues at all.  

Investigation: 11 

(but a passive perception of 24, if that helps)

Wripers paces around the others, covering ground on all fours, sniffing whatever seems "good." The smell of dead things was a surprise, but he's eaten worse. Far worse. He thinks about that time he brought Amari that bird, only for her to make it disappear when he wasn't looking. He wonders if that bird was good. 

[Passive Perception: 19]