Jasper dances around and attacks one of the spawned creatures that had attacked Maggwyn before moving away to stand between those creatures and the majority of his companions since some are in tough shape (if possible). 

(Mobile Feat to get away.)

Booming Blade Attack: 21
Weapon Damage: 7
Sneak Attack: 2
Thunder Damage: 7
Thunder Damage if the enemy moves: 13

Most Damaged Summoned Creature Wisdom Save against Toll the Dead - 15

After a series of attacks and spells from Crannoc and Maggwyn, one of the summoned creatures is slain (leaving four undamaged ones). As it is sliced through it returns to that same ichor that it came from.

Jasper leaps to another one that attacked Maggwyn and lands a large strike on it.

The creatures bite at each of you once.

Bite attack against Crannoc - Attack: 17 Damage: 9

Bite attack against Maggwyn - Attack: 9 Damage: 9

Bite attack against Miesha - Attack: 6 Damage: 9

Bite attack against Jasper - Attack: 13 Damage: 10

Crannoc continues to call out the vanished hag, "You do not belong here. What do you seek? Whom do you serve?"

He brings his spectral pine needle to bear on the most injured acid creature (the one that Jasper hit) and calls Temuth's Toll the Dead down on it.

Bonus Action:
Spiritual Weapon to hit:  20 + 2 from Bless = 22
Force damage:  12

Action:
Toll the Dead:  DC 18 WIS Save or 3 necrotic damage.

As the one creature came over to bite Maggwyn, she uses her reaction to stab him with her pole arm.  (she had disengaged and moved out of melee range)

Attack: 14 Damage: 8

She then continues her attack on the one that tried to bite her.

Attack: 27 Damage: 11

Attack: 12 Damage: 7

Adding bless to the two low attacks... cause of course I forgot

bless to attack #1: 3

bless to attack #3:  2

Quote from TaniHeron >>

 

Bite attack against Miesha - Attack: 12 Damage: 7

 ((MIesha is prone from the Spew Attack so I believe the bite attack here should be at advantage... Roll once more 'case a 12 misses.))

     Miesha uses half her movement to stand prone once more.  Miesha then makes two spear attacks and a Bonus Action butt end of the spear attack versus the one currently trying to bite her.  If she manages to put that one down she will move to whichever is closest (if within her remaining 15ft movement) and use remaining attacks on that one.

1st Spear Attack: 17 Damage: 9

2nd Spear Attack: 18 Damage: 8

Bonus Action Spear Attack: 23 Damage: 5

...

I forgot Bless again... make those attacks:

1st - 11 + 2

2nd - 17 + 4

Bonus Action - 19 + 1

...

Jasper attacks the creature that is after him before dancing away to set up future flanking against Maggwyn's foe.

Booming Blade Attack: 21
Weapon Damage: 8
Thunder Damage: 8
Thunder Damage if the enemy moves: 7

Saving Throw against Toll the Dead - 4

The damaged creature is felled by Crannoc's spell.

(Advantage against Miesha - Attack: 9 Damage: 9 )

Many of the attacks hit the creatures, leaving only three, heavily damaged ones remaining. The hag's shrill laugh calls out, echoing through the tunnels: "Silly Temuth-Spawn, our King does not abide by your pointless rules. You ought to back down before you get yourself into something that your leafy-patron hasn't prepared you for." She shouts one more order in that unfamiliar language. The creatures all turn their mouths up and disgorge all they can, the acid turning to ichor as their entire body is cast into the air to corrode your flesh.

As the entire room is filled with their ichor in their death throes, this works differently than previous attacks. Make a Dexterity saving throw (DC 15), taking half damage on a success and full damage on a failure.

Damage: 34

Maggwyn DEX save + bless:  20 + 3

Miesha Dex save: 3
…

Dex save: 12

Rerolling with Luck: 9

Is this acid damage?

Crannoc DEX Save:  18 + 4 from Bless = 22 (success)

Recoiling at the hag's strange words and the ensuing explosion of acid, Crannoc is able to avoid the worst of it and brings up an arcane hedge covered with moss and bracken to absorb some of the acid that does hit him.  (Casting Absorb Elements as a reaction to further half the damage).

Total acid damage taken = (34 / 2) / 2 = 17 / 2 = 8.

DC 10 CON Save to maintain concentration on Bless:  17 + 1 = 18 (success)

Crannoc looks around quickly to see if any of his companions need healing from the final, suicidal throes of the abominations.

Maggwyn jumps as clear as she can from the acid spray, but even getting half of the acid on her, takes her down.  She lays on the ground, unconscious.  

Jasper is about to be caught in the open as the acid explosion occurs but trips on something and actually avoids some of the damage via a fortuitous stumble. He too reacts with the Absorb Elements spells and hisses in anger as Maggwyn goes down. "Tree man, please help my apprentice. She is not blessed with nine lives."

If there is no further immediate danger (or perhaps even if there is), Crannoc moves quickly to heal his companion(s).

He checks Miesha first to make sure she is still standing, being the other healer in the group (in case something were to happen to him).  Seeing that she is, he moves to Maggwyn and touches her shoulder gently.  Cure Wounds:  7 hp healing.

She feels a strange sensation, the slightly pleasant, slightly gross feeling of having taken a warm, fully-clothed mud bath.  The rich minerals of forest soil helping to leach out the acid and soothe their burned skin and flesh.  Crannoc steps back and wipes his brow, still clearly disturbed by what just happened.

Still concentrating on Temuth's Bless, he muses aloud, somewhat helplessly:  "The... hag.  She mentioned her King.  This is part of something bigger.  It must be - I feel it.  Have felt it for some time now."  He looks around for any sign of the hag or other threats.

Perception:  25