Bilyur channels his time as an acolyte and points at the area in front of Xarkris. The toll of a bell rings out. Then he attacks Skulk 3 with a roundhouse kick. 

Action: Cast toll the dead.  The Invisible stalker must make a DC 14 WIS save or take 8 necrotic damage. 

Bonus action: Unarmed strike: 21 to hit, 6 damage. 

(Ignore the quarterstaff rolls, I wasn't thinking and thought I could cast toll the dead and attack on the same turn.) *facepalm* *second more violent facepalm*  

Bilyur harnesses his newly learnt cleric magic and sends a ringing, howling noise at the space that he expects where the Invisible Stalker is [DC 14 Wisdom Save: 8 ], before striking Skulk 3, taking out another significant portion of its health. 

The Stalker is thoroughly shook through by the blast of ghostly noise, though there is no indication that there is any loss of it’s air form to show its close to death or even any significant wounding. 

Status
- Invisible Stalker (Health: -11, Condition: invisible, Position: In front of Xarkris) .
- Skulk 3  (Health: -12, Attacks against it have advantage)
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown)

When it is Xarkris’ turn, he will focus on the Invisible Stalker the best that he can. He yells, “SHOW YOURSELVES, COWARDS!” I rolled a TO HIT with DISADVANTAGE and got a (10,17)+5 for a 15. I rolled for 7 points of damage with my battleaxe. 

Xarkris just managed to slice the invisible veil of air that holds the Stalker’s form together, and there is a light gust as some wind escapes, like blood would from a wound. 

Just Sly, Eggo and Sal remain! 

Status
- Invisible Stalker (Health: -18, Condition: invisible, Position: In front of Xarkris) .
- Skulk 3  (Health: -12, Attacks against it have advantage)
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown)

((we... we could have gotten a dinosaur mount ;_; bro you kill me . fossilized. i want a dinosaur mount hghgh ))

Salamander likes the burnt smell of crisp whatever in the air. These invisible-now-visible-monsters were all too much for him to wrap his head around, so he prefers to stick to the ones he can see. Though judging by what they did to Xarkris, they can sure pack a punch. 

He leaves his dust devil alone for now, instead focusing on his own invisible toxic concoction.  He crouches down and squints hard at his enemy, giving him the 'I'm watching you' glare. His tail spikes up. And like a horned lizard, he straight sprays this poison mist right out of his eyes. It is stained colored red. It lands right onto Skulk 3's ugly face. Salamander cleans up the 'bloody' mess with his nictitating membrane.

((Action: Cast Poison Spray on Skulk 3 with advantage (first roll  8 + 4 =12, second roll 16 + 4 = 20) so 20 for a whooping 1 + 2 (from Fury of the Small) poison damage))

Then with a burning fury, he does a cartwheel-like flip and handstands, throwing a small fireball from out his hands. 

((Bonus Action: Cast Produce Flame on Skulk 3 again with advantage for (first roll 18 + 4 = 22, second roll 5 + 4 = 9) so 22 for 2 fire damage))

Quote from Shiverquill >>

[Speaking of dinosaur mounts, I'm happy to share this since it was many dungeons ago, but the Golden Steed in Dungeon 4 that Irabella was looking for was actually a Prehistoric Figure Of Ancient Power, a Pyrite Plesiosaur, that would have made water traversal so much easier seeing as it gave water breathing and a swim speed. It was hidden behind that cracked wall where all the water was flowing out, and Quippyur even spotted a glimmer of gold through the crack!]

 [*10 morale damage*]
I'd have been happy not knowing that tbh. 🥲

Her arcane protection flares up, protecting Sly from a nasty claw strike. She raises her hand in defiance, forming another ice quill. She doesn't even try to target any of the creatures, instead aiming the projectile such that at least two of the creatures would be in the damage radius. [all creatures within 5 feet of impact need to make a Dex 14 save or take 10 cold damage]

If getting 2 creatures in the radius isn't possible or if she would hit an ally, Sly will instead cast toll the dead on the visible one. [DC 14 or take 12 necrotic damage]

[Ahaha, sorry guys, I thought it was super cool too and thought you might look for it, but, we’ve still got another 93 dungeons to go, so a dinosaur mount isn’t out of the question yet!]

Skulk 3 is burnt and battered by Salamander’s array of spells but manages to hold onto its undeath by a single thread somehow. It looks like even the lightest scratch could fell the twisted beast. 

Seeing as Sly can’t use ice knife without hitting several members of the party too, considering the enemies are right in front of them, she decides to try and end Skulk 3 seeing as it is so weak now with a spell similar to Bilyur’s. [DC 14 Wisdom Save: 4 ]

Skulk 3 fails the save and perishes, leaving no more visible enemies. 

Only Eggo Lass left now! 

Status
- Invisible Stalker (Health: -18, Condition: invisible, Position: In front of Xarkris) .
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown)

[[ New plan. Step 1: Find a way to go backwards in the Shadow Weave. Step 2: Get that plesiosaur mount. Step 3: ??? Step 4: Win. ]]

Concentration Save on Faerie Fire: 6+3 = 9 vs DC 10
Faerie Fire was not up this round.
Seems the skulks also have the perma-invisibility so here are some changes to other's actions.

1: Salamander would not have advantage on the attack against Skulk 3. And, assuming the perma-invisibility like an Invisible Stalker, would've needed to use his Hawk Spirit reaction to make it a flat roll. 
2: Sly could not see Skulk 3 and therefore could not cast Toll the Dead due to needing to see the target unless you're allowing the general area to count as seeing, such as Bilyur's Toll on the Stalker.

"Blasted skulk!" shouts Eggo Lass as the skulk hits her with a nice chunk of damage. "You'll regret that." She takes aim at the invisible stalker.

Eldritch Blast @ Invisible Stalker
To-Hit: min(3,12) + 6 = 9
Damage: 6+4 = 10 force

//if a skulk with known position is still alive following any changes, would redirect it to that

[Ha, with so many dungeons to get through we’d be hear for decades if you could go backwards again! Still, I could happily say that Irabella soon found it and since the only way is forwards, she might catch up to you! Maybe. 

Also I’ll be generous and say that the Skulk’s reflection was visible in the ink Sly cast since it was nearby and they have visible reflections, with the same applying to the Stalker and it’s ripples. The party would have picked that all up from the increased Perception granted by the Hawk spirit, which all makes sense. It’s only fair since the spell is pretty much useless otherwise, and it also means I don’t need to make any adjustments since Sly’s toll the dead would have killed on its own so no need to worry about Salamander]

Eggo blasts at where she thinks the Stalker is, but unfortunately misses. It is now the enemies turn! The Invisible Stalker is persistent in attacking Xarkris; something about him is causing the Stalker to target him. Meanwhile, the unseen Skulk slinks around and strikes at Salamander. 

- Invisible Stalker (Health: -18, Condition: invisible, Position: In front of Xarkris): Multiattack: Slams Xarkris twice:  23 and  25 to hit, 12 and 14 bludgeoning damage on a hit. 
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown) Attacks Salamander with its claws: 22 to hit, 5 slashing damage plus 6 necrotic damage on a hit. 

It is now the parties turn! 

Eggo Lass uses the reflections in the grease to pinpoint the invisible stalker and brings her hands to her forehead for a psychic spell.

Mind Sliver @ Invisible Stalker
Damage: 6 psychic
Save INT DC 14, -1d4 to next save on a fail

Seeing Xarkris under relentless attack, Bilyur moves to his side and reaches out to touch his back. "Fight on, my brave friend," He whispers, before stepping forward with a flurry of attacks, but sadly, without knowing where his opponent is, he fails. He then takes a defensive stance, ready to brush the invisible forces away. 

Movement: Move next to Xarkris. Dex Save 24. 

Action: Cast cure wounds on Xarkris for 16 points of healing. 

Bonus action: Flurry of Blows on the Invisible Stalker. Attack one: 8 to hit. Attack two: 6 to hit. Womp womp. 

Reaction: Reduce the highest damage attack against him by 14 damage. 

Xarkris is shocked by the 2 well-placed blows from the Stalker, and doubt begins to enter his mind. As pain wracks his body, he feels like defeat is near and the shame of potential failure stings much worse than his physical injuries. As he musters his strength to strike one more blow, he feels a warmth spread thru him and his pain recede. He catches a glimpse of Bilyur out of the corner of his eye and hears his encouraging words. A quick thought enters his mind, “I will repay you for this kindness, my friend”. With renewed vigor, he swings his battle axe at the area that he believes the Stalker is located..

I made a TO HIT roll on the Stalker at a DISADVANTAGE with a (20,12)+5= 17. I rolled damage of 13.

End turn.

((oops I forgot about the faerie fire but thanks DM for letting it be waved))

((Concentration for Dust Devil a measly 5 < 10 DC A Fail. ---> Salamander loses concentration))

Now without any of the skulks left (or so he thought) Salamander is left wondering where the last invisible enemy was until something claws at his sides in fury. He is left gripping his sides before he doubles over in pain. The dust devil that he had been focusing on disappears "GAH! WHAT IS THAT TYPE OF THING?!" 

Taking out his dagger ((Object interaction)), he flails his arms about wildly, trying to look for the source of his pain. His eyes sting with tears. 

((Action: Attack the general area around where the Invisible Stalker is WITH DAGGER (first roll: 6 + 5 = 11, second roll: 10 + 5 = 15) so 11 for 4 piercing damage))

He calls onto Fred for help, "LET ME AT 'EM. LET ME AT 'EM!" Then a small ball of fire ignites in his hands. Like a pitcher at the mound, he lobs the ball straight for the area by Xarkaris. "DUCK!"

((Reaction: Use Fred the Hawk Spirit to give himself Advantage if possible))

((Bonus Action: Produce Flame @the Invisible Stalker with ADVANTAGE for 22 (hopefully) (first roll: 18 + 4 =22, second roll: 1 + 4 = 5) for 6 fire damage)).

Sly ducks and weaves backwards, trying to get away from any more invisible forces. Since the battlefield is in complete disarray, she discards the notion of trying another ice knife and will instead fall back on the only thing left: throwing pen made of fire at the invisible stalker.

Attack with disadv.: 18 22, damage: 10 fire [lucky today, huh]

Eggo Lass sends a psychic beam at the Invisible Stalker, hoping to deal some damage and also damage its mental functions, at least temporarily [DC 14 Intelligence Save: 15 ] Meanwhile, Bilyur heals Xarkris and assumes a defensive position, but misses his attacks. Xarkris, now with a renewed strength, strikes the Stalker, whilst Salamander also misses his dagger strike. However, his Hawk Spirit guides him to strike the Stalker with a small flame, Sly similarly following suit.

- Invisible Stalker (Health: -47, Condition: invisible, Position: In front of Xarkris)
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown) 

It is now the enemies turn!

The Invisible Stalker just manages to withstand Eggo Lass's psychic attack, and moves to attack Xarkris again. It's strange how it won't let up on striking him in particular; there surely must be a reason, however now it realises that it is outnumbered so adapts its strategy slightly to attack Bilyur. Meanwhile, the final Skulk scratches at Sly. 

- Invisible Stalker (Health: -47, Condition: invisible, Position: In front of Xarkris): Multiattack:
  Slams Xarkris: 18 to hit, 9 bludgeoning damage on a hit.
  Slams Xarkris: 20 to hit, 8 bludgeoning damage on a hit.
- Skulk 4  (Health: Full, Condition: invisible, Position: Unknown): Attacks Sly with its claws: 10 to hit, 7 slashing damage plus 1 necrotic damage on a hit.

It is now the party's turn! 

[As per how the Stalker works and the lore behind it, it should technically only go for Xarkris, but I feel bad so I'm happy to say it'll adapt for the circumstances]

Eggo Last goes for another Mind Sliver at the IS.

Mind Sliver @ Invisible Stalker
Damage: 6 psychic
Save DC INT 14, -1d4 on next save

[[ Oh my gosh. I am on a roll with Mind Sliver damage! ]]