(Dekhan already tried. It's a skull, with limited facial expression, plus you can't see it, plus its voice is somewhat muffled through the cloak, so it's a very high DC.)
With a nod, Incantis sends Zhudala north; she flies north. Incantis remains where he is, and after a moment he speaks to you all telepathically: The tunnel curves west, but nothing to see yet.
"ok, we leave forge. You come. We find spider. We help stop. Strix n Skull. Pals for-evs!"
Strix drags the skull east.
(He can get to the other side of the skull without moving it, then spend his remaining 40 ft on double-cost dragging to get to the start of the passage east, I think? Ready an action to bash him off the wall if he tries any funny business. )
This post has potentially manipulated dice roll results.
When it's his turn-ish, Scupper will hit the stealth (is pass without a trace still active?) and dodge ahead of Strix just to keep sight of other hallways and such. He's not really all that perceptive so probably more or less architecture as opposed to details and ambush. Far as he's concerned, this whole stalling with the skull is only going to last so long.
Scupper darts east, with his thirty feet of movement taking him just past Strix. As he is being stealthy, he only moves thirty feet, not sixty.
The voice comes, weary and irritated as well as muffled from beneath the cloak. Well, you can't say I didn't warn you...
Strix, you hear words of a magical spell of some kind from the skull. As you have an action at the ready, you can if you wish attempt to hit the skull, or bash the skull against the wall or floor, in an attempt to disrupt the spell. For the sake of simplicity, please treat either as a regular attack.
This post has potentially manipulated dice roll results.
As far as I can see, there's no RAW for interrupting a spell in this fashion, but I want to give you a chance this time. So please treat this as an exceptional case, because you have the enemy grappled. I'll do it case by case, but in general, interrupts are not a thing. The skull will make a CON save to keep the spell, and will cast it on initiative.
At the skulls words, Scupper turns about on the bagged abomination:
No! Ye didn't warn us! Ye complained and threatened but made no real attempt at trying te establish anything close to a reasonable dialogue. Plus yer a giant flaming skull and have yet to give us a reason te trust ye or yer word. Fiery skinless heads have been dishinest before! Pirates use skulls all the time te sew fear and mistrust! I should know. I used te be a pirate. So what is yer warning exactly and what is the dark elf doin' because the forge is definitely running...or starting...or...forging...
I'm not quite sure why I asked you to roll initiative again. I wasn't feeling great yesterday - I guess I was worse than I thought! Nevertheless, let's stick with the new initiative from this round - it does work in your favour, more or less.
Actually, scratch all of that, it makes no sense whatsover. You are all already in initiative. Let's keep the initiative order from before. Sorry folks!
This post has potentially manipulated dice roll results.
Strix, your weapon strike hits the skull, but it continues casting and completes its spell. There's a pause for a fraction of a second, and then the cloak, your hands, and the air around you erupt in fire.
Strix and Scupper, please make a DEX save. You take 35 fire damage on a failed save, 15 on a successful one.
The cloak is ash, and the skull floats free; it rises twenty feet and gives Strix a murderous grin.
(Dekhan already tried. It's a skull, with limited facial expression, plus you can't see it, plus its voice is somewhat muffled through the cloak, so it's a very high DC.)
With a nod, Incantis sends Zhudala north; she flies north. Incantis remains where he is, and after a moment he speaks to you all telepathically: The tunnel curves west, but nothing to see yet.
Incantis takes no other action.
Strix is up.
"ok, we leave forge. You come. We find spider. We help stop. Strix n Skull. Pals for-evs!"
Strix drags the skull east.
(He can get to the other side of the skull without moving it, then spend his remaining 40 ft on double-cost dragging to get to the start of the passage east, I think? Ready an action to bash him off the wall if he tries any funny business. )
Strix, Shifter Shadow Monk in Lost Mines of Phandelver ¦ Sihegiall Human Soulknife Rogue in In Search of Molly McGuffin
Strix moves east, dragging the grappled skull with him.

Zhudala is still to the north where she was in the previous map.
Varinth is up.
Varinth tries to catch up with Strix and the Skull
I'm shorry about this Míshter Skull washit you're guarding?
Varinth is able to dash up to stand next to Strix and the skull.
Dekhan is up.
When it's his turn-ish, Scupper will hit the stealth (is pass without a trace still active?) and dodge ahead of Strix just to keep sight of other hallways and such. He's not really all that perceptive so probably more or less architecture as opposed to details and ambush. Far as he's concerned, this whole stalling with the skull is only going to last so long.
Stealth 20 (without additional +10)
Perception 9 (with hooded lamp)
"Skull! What dangers lie here?" Incantis asks.
((Sorry for the absence, the work/school year started up and I've been swamped))
Incantis, half-elf warlock (great old one) 4/bard 1 ● Thorok Earthhand, hill dwarf mountain druid 6/grave cleric 2
Cragmyre Ironseed, earth genasi ancestral barbarian 3 ● Cyrus Natriallae, aquatic half-elf warlock of the deep 3
Dekhan remains where he is.
Round Three:
A: Scupper
B: Flameskull-in-a-red-cloak
C: Incantis and Strix
D: Varinth
E: Dekhan
Scupper darts east, with his thirty feet of movement taking him just past Strix. As he is being stealthy, he only moves thirty feet, not sixty.
The voice comes, weary and irritated as well as muffled from beneath the cloak. Well, you can't say I didn't warn you...
Strix, you hear words of a magical spell of some kind from the skull. As you have an action at the ready, you can if you wish attempt to hit the skull, or bash the skull against the wall or floor, in an attempt to disrupt the spell. For the sake of simplicity, please treat either as a regular attack.

In the meantime, everyone please roll initiative.11 for 9
(Rolling one handed staff attack for simplicity)
Init : 4
"This mean not pals?"
Strix, Shifter Shadow Monk in Lost Mines of Phandelver ¦ Sihegiall Human Soulknife Rogue in In Search of Molly McGuffin
As far as I can see, there's no RAW for interrupting a spell in this fashion, but I want to give you a chance this time. So please treat this as an exceptional case, because you have the enemy grappled. I'll do it case by case, but in general, interrupts are not a thing. The skull will make a CON save to keep the spell, and will cast it on initiative.
Skull's CON save: 22
He makes that quite handily.
Skull's initiative: 7
Less good.
Initiative 16
Initiative: 4
Initiative 8
At the skulls words, Scupper turns about on the bagged abomination:
No! Ye didn't warn us! Ye complained and threatened but made no real attempt at trying te establish anything close to a reasonable dialogue. Plus yer a giant flaming skull and have yet to give us a reason te trust ye or yer word. Fiery skinless heads have been dishinest before! Pirates use skulls all the time te sew fear and mistrust! I should know. I used te be a pirate. So what is yer warning exactly and what is the dark elf doin' because the forge is definitely running...or starting...or...forging...
Initiative: 14
Incantis, half-elf warlock (great old one) 4/bard 1 ● Thorok Earthhand, hill dwarf mountain druid 6/grave cleric 2
Cragmyre Ironseed, earth genasi ancestral barbarian 3 ● Cyrus Natriallae, aquatic half-elf warlock of the deep 3
I'm not quite sure why I asked you to roll initiative again. I wasn't feeling great yesterday - I guess I was worse than I thought!
Nevertheless, let's stick with the new initiative from this round - it does work in your favour, more or less.Actually, scratch all of that, it makes no sense whatsover. You are all already in initiative. Let's keep the initiative order from before. Sorry folks!
Strix, your weapon strike hits the skull, but it continues casting and completes its spell. There's a pause for a fraction of a second, and then the cloak, your hands, and the air around you erupt in fire.
Strix and Scupper, please make a DEX save. You take 35 fire damage on a failed save, 15 on a successful one.
The cloak is ash, and the skull floats free; it rises twenty feet and gives Strix a murderous grin.
Incantis and Strix are up.
((Would you say an hour has past since the ghoul fight?))
Incantis, half-elf warlock (great old one) 4/bard 1 ● Thorok Earthhand, hill dwarf mountain druid 6/grave cleric 2
Cragmyre Ironseed, earth genasi ancestral barbarian 3 ● Cyrus Natriallae, aquatic half-elf warlock of the deep 3