(I do not do flanking. Considering half the time I do theater-of-the-mind for convenience, it is too much work for me to micromanage flanking when we use maps.)

Shadow Demon CON save vs DC 16 Moonbeam. 34 damage on a fail (vulnerable to radiant damage), 17 damage on a save. Roll: 3

Spar's first swing only passes through smoke, but the follow-up hits for 11 damage.

Drusk swings his mace at the Shadow Demon. (rolls in Game Log) To-hit: 10 which misses

Shadow Demon continues attacking Drusk. (disadvantage due to Daylight) Attack: 9 Damage: 10

The drow mage runs north from behind the pillar at H12, and casts Cloudkill.
The green circle is the spell effect. Visibility is heavily obscured (entirely blocked visually).
(The mage was headed to C13, but with Cloudkill blocking sight, she could have turned around and returned south.)

Everyone in the area of effect (except for Hildigrim), at the start of your turn, roll CON save vs. DC 14 poison.
22 poison damage on fail, 11 on success.
(Shadow Demon is immune to poison. Drusk passed the CON save in the Game Log with a 22.)

Party is up.
Initiative order: Hildigrim, Spar, Jorin, Drusk, Quillary ; then drow mage, shadow demon

I'm actually at A5. I'll roll in case enough of the cloud is in that square to affect me. Rolled a 1 (+5=6), so rolled again (halfling luck) and got a 17 the second roll. Let me know if I should subtract 11 or 0 due to I don't know if I'm really affected by the cloud. Also, was Volo in that area? If so, even if he saves, 11 is enough to kill him.

Hildigrim scurries from A5 to A3 and looks at the cloud. Not being able to see anything, the halfling pauses, trying to think what to do next. Finally, he dashes to E1 and starts yelling, "Hey! Over here!"

(Imma wait for my turn this time… ;)

Soar manages to hold her breath and avoid most of the poison (rolled a 12+7=19 in the game log, not sure if you can see but I screenshotted it just in case) but as her eyes were looking to see if the creepy darkness ball revealed anything, she did see the mage dart north. She runs headlong NE, down the stalagmite and  to A9, A10, or even A11, depending on how we count diagonals. (Not sure if this prompts an AoO given no visibility, or just disadvantage.) She doesn’t need to see the mage, though the daylight from behind her head is illuminating this side of the cloud fairly well, and hopefully giving the mage a headache. She could drop another darkness hellhole on her, but not wanting to risk more time than necessary with the demon and the cloud, instead she clacks her teeth together hard. She casts shatter at 3rd level, centered just beyond where she sees the mage, or judges her to be, and so that Spar is out of range.

14 thunder damage on a failed CON15 save, half on a success.

Quote from DirtyDogP >>

I'm actually at A5. I'll roll in case enough of the cloud is in that square to affect me.

(My bad. At A5, would be affected, for 11 poison.
Since Hildigrim started the turn in the cloud, you have the choice of going back west or forward to the east, to get out of the cloud.
You can change your movement, given that info.
Since Hildigrim can Dash as a bonus action, he could reach column 13, and shoot the mage if she is in sight.

Given Volo's speed, I assumed the owl is somewhere like A1, away from the others and not in the cloud. But Volo wouldn't be able to Help without going into the cloud and taking poison.)

CON cave vs the poison: 15

Going to wait a tick to see what Hildi does, as i was going to run towards his voice over in E1, but I might change that depending on what he does based on Quasi's last post.

Oh man, missed it by 1...Jorin is looking far rougher than usual at the moment, lol.

Also, reading the description of cloud kill, I'll have Jorin try to climb on top of the stalactite he's next to in order to try to get above the poison cloud.  And then would it be possible to jump from rock to rock towards the west edge of the cloud?

(It’s a 20 ft radius sphere right? So that would seemingly go to the top of the cavern, unless it was centered below us, and thus means climbing above it is impossible? Maybe I’m wrong. What I don’t understand in the spell description is what happens on subsequent turns - does it flatten like a pancake? Expand outward in one direction? All directions?)

I’m hoping the mage fails her con save to take full damage and kicks the bucket, or if not, rolls super low on her concentration check and the spell drops. Which, speaking of, Spar needs to roll a concentration check for hex.

11

(Also did my roll for the 19 con save show up for anyone in the game log? I’m trying to be more competent in that area given dice roller issues here. I have a screenshot of the result, which I could try to share in the PM thread, if we don’t have a discord option.)

(As rkmobius said, it is a 20' radius sphere, cast 5' above ground in a cavern with a 20' ceiling, so you'd have to be at the edges before there is room to go over the cloud.
The damage happens at the start of your turn, or the first time you enter the cloud if you don't start in it.
If you start in it, you can move around as much as you want without more damage. (You only have to worry where you are at the start of your next turn.)

You all saw the mage at F13 when she cast the cloud. Even though you aren't certain if she ended at C13, because the cloud blocked your sight, you know she is somewhere in the eastern part of the cavern.
The Shadow Demon has poison immunity, so can ignore the cloud.)

Ah ok, Jorin will use all 40 ft of his movement speed to get to B10 by way of E3, D4, C5-8, B9, B10

(Hildigrim’s action was to dash right? So we’re not waiting on anyone?)

(I'm still waiting for Drusk, yes?)

Quote from rkmobius >>

(Hildigrim’s action was to dash right? So we’re not waiting on anyone?)

(There was some confusion about Hildigrim’s move, since I had him at the wrong location.
If he started out of the cloud, he was going to back up to the west.

Since Hildigrim actually started inside the cloud and took damage, there is no penalty if he charged forward to the east.
I wanted to give him that option, since I messed up on the initial position.)

OH man, i'm sorry, just remembered i have these things called actions that can be used for something other than axe swinging.  Jorin will use his action to dash a bit further to B13, hopefully to head off the mage's retreat.

So, to put all of Jorin's turn in one post:

Failed con save vs the poison, then 40 ft of movement to B10, then action -> dash to B13.

(I'm hoping that Jorin's action happens after Feldspar's action -- she wouldn't cast shatter if Jorin ran in there first! Assume he goes after given the initiative order...)

Since Hildigrim wouldn't have seen the mage cast the spell, and he is just on the edge and (I'm imagining) it would be ever so slightly less on the edge and inviting for an exit, I'm still going to say that Hildigrim moves to E1 and starts yelling to hopefully bring his mates his direction out of the cloud.

So that’s his action?

Hildigrim backs up to the west, by the entrance to the cavern at E1. He sees the cloud of poison gas moving to the west, and realizes the cloud is going to envelop him before he can move again. (Cloud is moving 10' west on the drow mage's turn.)

Jorin sprints in a clockwise pattern, staying clear of the shadow demon. He bursts out of the cloud, and is surprised when he almost runs into the drow mage at B12. (The mage is also surprised, as she was looking around the corner, anticipating that her pursuers were going to be using the E and F rows towards the cavern exit.) Although he cannot attack, he spins around her to end up at C13, blocking off her path to the exit.

The shadow demon makes an AoO at Feldspar. (The cloud is obscuring vision, but she does have Daylight next to her skull. The attack is with disadvantage.)

• Attack: 16 Damage: 11

After emerging from the cloud, Feldspar is barely able to pick a spot on the north wall where the Shatter effect won't affect her or Jorin.
The thunder damage finishes off the drow mage. (Even a successful save does 7 damage, more than the mage had left.)

Combat is over.

With the death of the drow mage, the summoned shadow demon dissolves into smoke, and the Cloudkill spell ends.
(No damage to Quillary or Drusk since the spell ended before the start of their turns.)

The shatter spell has destroyed much of the drow equipment.
You are able to find 2 doses of drow sleep poison. (Treat it like the basic poison described in the PHB, but instead of adding poison damage, it is DC 13 to cause the poison condition, and failing by 5 or more causes sleep.)
There is also a journal book on the drow mage. Most of it is shredded, but there are some pages intact.

(The Shatter spell only deals damage to nonmagical items that are not being worn or carried, so I assume the journal and anything the drow were carrying are fine.)

Jorin spits on the drow mage and then slumps against the rock and sits, battered more than usual from the fight.

"I might could use a small rest to bandage myself."  He manages a weak smile and adds, "Curse the gods and my lack of adventuring ale."