"Be careful lads, looks like there is something around here that likes to feast on devils and it may still be around" Tibi whispers as he continues to lead the party down the sloping passage on the far right side.

Moses isn't sure how to respond to Tibi, but he doesn't want to be rude, so he simply nods in response.

As Tibi moves down the shaft the others who are walking notice that the scab transitions from being soft and spongy to hard as rock. Ahead a 20-foot-wide chamber opens up.  You see motion in the room as Lulu suddenly calls to Tibi to stop. Ten small, snarling demons covered in matted gray fur claw and bite a hole into the hard, scabby floor. A demon made of shadow flies over the smaller fiends, screaming at them in Abyssal.  They are so busy at their work that they do not see you.

"I...I sense...the presence of Crokek’toeck nearby.  That is the demon lord Yeenoghu’s pet.  If there are demons ahead the demons are trying to free Crokek’toeck.  We need to stop them" Lulu says.

Tibi recognizes the smaller demons as dretches and the demon made of shadow to be a shadow demon.

You get a surprise round to attack if you choose to do so.

Dretch:

Shadow Demon

Drabash draws his battleaxes and prepares to advance on the demons, 'Come on then, let's get them.' he whispers.

TIbi launches into the air Rapier and shortsword extended as he swoops silently like the type of bird his clan are named for at the Shadow demon striking twice with his rapier and once with his shortsword before continuing past and banking in order for a return strike
1st Rapier attack = Attack: 29 Damage: 9 + lunging attack = extra 2
2nd Rapier attack = Attack: 20 Damage: 13
Shortsword attack = Attack: 24 Damage: 12
Backstab = 8

In case a second set of rolls is needed

1st Rapier attack = Attack: 17 Damage: 15 + lunging attack = extra 3
2nd Rapier attack = Attack: 14 Damage: 12
Shortsword attack = Attack: 24 Damage: 12
Backstab = 6

Kaelani sends a flash of light streaking towards the shadow demon, then draws his +1 longsword and advances into the fray! (Guiding Bolt at 1st level w/ advantage for surprise: Attack: 28 Damage: 16)

Moses is surprised at the boldness of these strangers, but he isn't one to stand idly by. He raises his staff and prays for guidance on Tibi, Drabash, Kaelani and himself.

Bless (at second level) on the four of us.

I need a surprise round action from Drabash and then we will enter initiatve

Initiative 

Moses 11, Tibi 23, Kaelani 19, Drabash 5, Dretches 6, Shadow Demon 21

Initiative order:

Shadow Demon (?), Drabash (104/104), Kaelani (68/68), Dretches (?), Tibi (81/88), Moses (63/63)

Drabash launches himself into the fray, attacking the shadow demon.

swinging his battleaxe+1: Attack: 20 Damage: 13 slashing damage

and his battleaxe: Attack: 16 Damage: 8 slashing damage

and his extra attack battleaxe+1: Attack: 30 Damage: 16 slashing damage

In a furious onslaught the Shadow Demon is quickly cut down and you turn your attention to the Dretches and slay 2 of them as well.  The remaining Dretches stop digging and move to defend themselves.

Drabash and Kaelani are up again

Initiative order:

Drabash (104/104), Kaelani (68/68), Dretches (?), Tibi (81/88), Moses (63/63)

Flame-like radiance descends on one of the dretches, bathing it radiant energy unless it can dodge out of the way! (DC17 Dex save or take 8 radiant damage.) He maintains some distance between himself and the demons unless they move towards him...

Drabash continues to cut a swathe through the dretches, wading in and swinging his battleaxes.

swinging his battleaxe+1: Attack: 16 Damage: 13 slashing damage

and his battleaxe: Attack: 18 Damage: 11 slashing damage

and his extra attack battleaxe+1:  Attack: 12 Damage: 10 slashing damage

2 more Dretch are killed.  3 of the remaining attack but only 1 is able to claw Drabash.

The other 3 let out A 10­-foot radius of disgusting green gas that starts to fill the room and Moses, Drabash and Kaelani must succeed on a DC 11 Constitution saving throw or be poisoned until the start of their next turn. While poisoned in this way, the target can take either an action or a bonus action on its turn, not both, and can't take reactions.

Tbi and Moses are up followed by Drabash and Kaelani again

Initiative order:

Drabash (104/104), Kaelani (68/68), Dretches (?), Tibi (81/88), Moses (63/63)

Kaelani DC 11 Con: 10

The aasimar coughs a little, then redirects the radiant flames towards another dretch. "How about you suck some of this?!!?" (DC17 dex save or take 10 radiant damage!)

Tibi pivots on one wing and swoops back at the Dretches:
1st Attack - Rapier:Attack: 17 Damage: 10
2nd Attack - Rapier:Attack: 18 Damage: 13
3rd Attack - Shortsword:Attack: 15 Damage: 10
Backstab - 11

Before using Fancy Footwork (Wingwork?) to continue past the creatures

Because of his "Piercer" feat the shortsword critical does an extra 3 of damage

Everybody is blessed and gets a d4 on all attack rolls and saving throws.

DC 11 CON save: 18 + bless: 2

Drabash snorts, "I've smelt worse stuff coming from my mother's armpits." Casually breathing and dismissing the odour. Saving throw: 14

He then continues to cut a swathe through the dretches:

Battleaxe+1: Attack: 19 Damage: 12 +Bless:2

Battleaxe: Attack: 20 Damage: 10 +Bless:1

Battleaxe+1: Attack: 29 Damage: 7 +Bless:3

16

A moment later the slaughter of the Dretches is complete. Dretches are among the weakest of demons and they were easy to overcome.  You have been able to stop them from digging and the shadow demon leading them was unable to leave and report your presence in the scab.

A passage to the right runs down and another runs back to the left at a shallower angle down.

Tibi cleans his weapons and resheaths them before leading the party off down to the right.

Drabash has a quick look at the body of the shadow demon to see if it was carrying anything interesting and at the area the dretches were digging, then assuming nothing interesting is noticed he follows Tibi.