Chroma elbows the ogre's chest before grabbing the shoulder and bringing it down for a knee to the sternum.

Action - Unarmed Attack: 27 Damage: 8
Bonus Action - Unarmed 11 Damage: 9

She retreats a step or two if the ogre falls and will crush any grubs with her hands, which she promptly wraps in one of her blue sashes to avoid directly contacting the grubs.

Chroma's attacks promptly cave in the ogre's chest, stopping his heart at long last. He lands with a heavy thud on the floor, across the channel of water. The water comes in contact with the ogre's leaking fluids and the crusting action promptly turns the ogre into a bizarre and grotesque abstract sculpture, as if it just sprouted red coral out of its body.

Beyond the ogre, the fuse continues cracking and popping its way towards the main hive.

The orcs, also badly infested, their torsos bloated and leaking steadily, are just about in combat range. Faerieth has a moment to act (As she the only one who didn't before the ogre got pasted)

((My bad thought I posted))

Faerieth lifts up her staff and readies herself for the fight ahead. ((Ready Shillelagh for when a monster gets in melee range of her.))

The group see that they only need to hold the orcs at bay for a few moments as the fuse actually starts getting louder as the chain reaction finds more crust and the more violently it breaks apart, the bigger the shattered chunks become and cause more damage, like exploding a Prince Rupert's Drop ((https://www.youtube.com/watch?v=xe-f4gokRBs&t=336s)).

The infested orcs square off, an even 4 on 4. The only one who's armed is the one using the old Tyranthraxus banner as a spear. He takes the front, opposite Chroma, who has taken point.

The orcs are hesitating, their attention split between the fuse and the group, causing them to act last.

Chroma will take the opportunity to slam down on the orc with the makeshift Tyranthraxus spear's instep, elbowing it directly in the jaw afterwards. 

Action - Unarmed Attack: 26 Damage: 7
Bonus Action - Unarmed Attack: 14 Damage: 7

The orc stumbles back but doesn't fall and keeps his grip on the banner.
Now that she's close to the infested orcs, she can see that their fingers have been worn so much from doing what looks like ... digging with their bare hands, working  building their hive, that the ends of their fingers are encrusted. They must have been exposed to water at some point and the crust just became part of their hands, making for intimidating claws... it's probably also why they're not armed, they can't hold tools anymore.

Qiran glances about - their plan seemed to be working.  With another brief arcane chant, a spectral red dragon rises from his hand and roars at the infected herald - casting Toll the Dead.  After casting the cantrip, he retreats another 30 feet towards their exit.

(( 9 necrotic damage.  Wisdom DC 14 negates. ))

The banner clatters to the floor as the orc lets out a gurgle and falls to his knees, the grubs slipping out of his body.
The cracking is getting louder despite it moving further away. From the sounds of things, it's taking out the structures in front of the main hive with startling violence. The creatures down the tunnel can be heard shrieking among themselves.

Faerieth takes her quarterstaff and swings it at one of the creatures, the staff's embellishments seeming to come to life as she swings it.

Bonus Action: Cast Shillelagh

Action: Quarterstaff Attack [Shillelagh round 1/10]
Attack: 22 Damage: 10

The orc's head spins around from the impact, but he stays standing, just barely. Krinix has just enough time to act before the remaining three pull themselves together enough to attack.
A loud screeching can be heard down the tunnel as the cracking suddenly raises in volume, almost comparable to fireworks going off in sheer volume.

Kronos already described his move I think, previous page

((That was for the ogre, there's currently 2 uninjured and 1 badly injured orc still standing, but if you want to just take the same action as before, roll attack and damage))

((Or I can :P))

Krinix's fire bolts: Attack: 17 Damage: Unable to parse dice roll.  damage: 7\

A second orc goes down, its grubs popping.

The last two that remain rake and claw at Chroma:

Attack rolls: 24  19

Damage: 3 5  their claws sting, but Chroma's tough scales withstand the vicious assault.

It's then that the hive cracks apart violently, and a rush of water can be heard. The shrieks of those at the hive as the water pours through is still clearly heard even as chunks of the structure shatter apart and shred the inhabitants. The remaining two orcs stiffen and shriek, as if in agony, rendering them helpless, though a wall of water is coming straight at the group.

((Thanks, missed that post I guess))

Krinix turns and runs away from the water

(Athletics check, all around! DC 8)

Athletics: 11

Athletics! 18

Chroma frowns at the assault before realizing retreating from the cavern is now their main priority. 

Chroma's so ahead of the waves that she can give advantage to the others for their athletics, helping keep their feet under them.

krinix athletics with advantage 17