Molliver shrugs. She and her three brigganock companions lead the party down through several tunnels that lead to the chasm but stop short of entering it.

The route ends at a gaping chasm, on the far side of which is a grotto full of stalactites and stalagmites. A truss bridge constructed of intricate wooden struts and beams spans the one-hundred-foot gap across the chasm. Beneath the bridge is darkness dotted with purple lights.

“Well,” declares Molliver, “here we are at jolly old Rivenwish Chasm. Best stay on the bridge and not dillydally.”

The bridge is 5 feet wide, 100 feet long, and looks reasonably sturdy. There is nobody upon it, nor are there any obvious dangers.

"When you get to the other side, go see Obud," she adds.

(Single file! Who's first?)

Ben:

”Let me go in the middle, that I may help those on either side of me,” suggests Ben.

Matilda heads across...

Matilda takes a few steps forward onto the wooden bridge. She doesn't get far before three disembodied skulls rise out of the chasm, glowing with dim green light. Blazing green flames flicker from the backs and sides of the skinless skulls as they laugh maliciously at Matilda, taking up positions 10 feet above the bridge.

Then they unleash fiery rays from their fiery eye sockets at her.

Roll initiative!

Flaming skulls: 12

(Ben's in the middle somewhere, but who's behind Matilda? What order are you all in?)

Pud’s Initiative: 22

Pud will take up the rear. 

Titaani, who is behind Matilda, lets out a frightened squeak at the sight of the skulls. "Ah! I knew this was a bad idea!" 

Initiative: 9

Ben's Initiative:  7

Initiative- 10

Matilda shot a scathing look at the small fay creatures, " When we have rescued the Queen and she's back in charge we are making a full report about you little buggers.....this is a breach of hospitality, a breach of contract and child endangerment. "

Initiative:

Matilda: 23  (first in line!)
Pud: 22  (in the rear)
Flaming skulls: 12
Titaani: 9  (#2 behind Matilda)
Ben: 7 (in the middle)
Horatio: 11 (or did he stay behind to set up shop?)
Tiny: 23
Elkhorn: 11
Amidor: 21
Pollenella: 18
Gleam: 16

(Did I forget anyone?)

Matilda makes a break for the other side of the chasm, dodging and weaving.

Acrobatics- 4

Action- Dash

Cunning Action-Dash

Pud conjures up a sizzling bubbling arcane ball of acid and hurls it at the flaming skulls. He then backs up 15 ft to create some space for the other members of the party. 

action: cast acid splash at the skulls. Make a dc 15 dex save or take 8 acid damage.

move: back up 15 ft. 

(( Horatio would NOT have separated from the group again! He would be near the front, perhaps behind Titaani? ))

Horatio would call to the others, "Quickly, to the other side before they burn the bridge down!" (( Free Action: Speak ))

He then looks at the center skull, "Have mercy!" (( Reaction: Stone Rune, DC 13 Wis Save or it is charmed ))

Angry at their circumstances, he suddenly becomes large (gaining reach to 10') as he punches at the other skulls. (( Bonus Action: Giant's Might - Attack One: 15 to hit, 14 damage if hits - Attack Two: 16 to hit, 16 dmg if hit ))

Matilda's attempt to dodge and weave becomes more of an exercise in staggering and careening, but she runs 30, 60, 90 feet... directly under the three flaming, flying skulls. They sneer and laugh at her, and then growl at her in Sylvan, "සුභ පැතුම්!"

(If your character understands Sylvan:)

Pud, all the way in the back, tosses a ball of arcane acid at the first one (they are each about 10-15 apart from each other, about 10' above the bridge.)
It tries to dodge: DC15 Dex Save: 12
Then Pud backs up further.

Horatio tries to reason with the center skull, but it just laughs. (Immunity: charm) 
Growing twice his size, Horatio swings at the first skull. Both fists connect, cracking off a large piece of blackened bone from the unnatural horror which sizzles as it falls. The skull is in very poor shape.

Two of them unleash their flaming eyes on Horatio, and the third on Titaani.
#1 Fire Ray #1 vs Horatio. Ranged Spell Attack: 16. Hit: 8 fire damage.
#1 Fire Ray #2 vs Horatio. Ranged Spell Attack: 25. Hit: 12 fire damage.

#2 Fire Ray #1 vs Horatio. Ranged Spell Attack: 8. Hit: 14 fire damage.
#2 Fire Ray #2 vs Horatio. Ranged Spell Attack: 21. Hit: 11 fire damage.

#3 Fire Ray #1 vs Titaani. Ranged Spell Attack: 24. Hit: 15 fire damage.
#3 Fire Ray #2 vs Titaani. Ranged Spell Attack: 20. Hit: 10 fire damage.

Titaani and Ben may act next!

Tiny, who had stayed behind on solid ground, will use his movement to rush up to just behind where Pud is. If he can't reach Pud with only his movement, he will take the dash action. If he can reach Pud with only his movement, he will take the help action. He does this by nuzzling his head against Pud, attempting to imbue him with some of his fey magic. 

Ben:

”Continue moving forward—the trial is not to kill the skulls, but to cross the chasm,” suggests Ben.  He moves as far forward as he can (up to 30 feet) and calls down radiant energy on the wounded skull.

Sacred Flame:  DC 14 Dexterity Save or radiant damage = 14

" Hey! Bony 1,23. Why are you attacking my friends? Those little ones are the ones who said we had to cross, its their fault."

Persuasion- 19

Titaani winces as her hair catches fire, causing her to desperately pat it out. Screwing her eyes tight, she focuses on her crystal. 

"Titania, please, if you care at all," the little gnome whispers. "Prove it by sending someone to help."

Opening her eyes, Titaani looks around in disappointment before noticing that a shard of her crystal has broken off into her hand. Wide eyed, the gnome backs up a bit as the shard grows into a large, crystalline fey, with a glowing shortsword. After leaning down to gently pat Titaani on the head, the fey then rushes forward to attack the skulls with its shortsword. 

Shortsword attack: To hit - 18 Damage - 7 piercing and 2 force

(Spell used - Summon fey. Fey type: Tricksy)

Tiny pushes to the back of the line to help Pud.

Ben pulls down a flame-like radiance upon the first skull. DC14 Dex save: 18

Matilda calls out to the third skull, which turns to grin at her, responding in Sylvan:

Titaani calls forth a fey spirit, one in a dark, tricksy mood. It climbs atop Horatio's shoulders and slashes at the half-broken skull with a black short sword.

And it succeeds - smashing the first skull into fragments, which fall into the chasm. But two more remain.

Gleam's mask turns a brilliant bluish-white, and releases a beam at the second skull.
Gleam Moon Ray: Ranged Spell Attack: 17. Hit: 12 radiant damage. DC13 Wisdom save: 3 ...

The second skull vanishes, and in its place a small greenish-black bat appears, flapping wildly overhead.

Elkhorn produces two kitchen knives, and flings them (far-range) at the third skull.
Dagger Ranged Weapon Attack #1: 8. Hit: 3 piercing damage.
Dagger Ranged Weapon Attack #2: 16. Hit: 3 piercing damage.

Amidor produces a small leafy sling, and likewise attempts a long-ranged shot at the third skull. "Begone, flying heads!"
Seed Sling Attack: 9. Hit: 5 bludgeoning damage.

One skull and one bat remain.
Matilda, Pud (helped by Tiny), Horatio, and Tiny may act next.