Blood is starting to be mixed into the water from all of the wounds.

On the Monster's second turn one of them will swim forward enough to get with in 15 feet of all of you and cast thunderwave.  Every one needs to make a con save DC 13 on a fail you take 6 thunder damage and get pushed back 10 feet (which means hitting the wall so you will take damage as if you fell, so half of 6) on a success you take half of the first damage and do not get pushed back.  He will then use the remaining of his movement to get to the wall, staying 10 feet away from everyone and then cast lightning bolt.  If you failed the con save you now need to make a Dex save or take 27 lightning damage.

For the rest of the monsters I want to wait to see how this part plays out so please hold off on taking your next turns. 

If you save on the con save you only take 4 damage.

if you fail the con save you take 10 damage. and have to make a Dex save (DC 13 sorry for not putting it above)

If you make the dex save you take 19 points of lightning damage

if you fail the dex save you take 39 points of lightning damage.

Kraven Con Save: 9

And if needed a Dex Save: 15

Kuatho con save : 9 

Kuatho Dex save : 13 

Jecob CON save (from Game Log): 18

(If anyone is within 10', you do get a +3 from the paladin Aura of Protection.)

(I didn't take a second round action.
After putting up an ice canopy in the first round, Jecob moves to the front of the group for the second round.
Floating about 5' up, and Readies an attack when an enemy gets within melee range.
That wouldn't affect the enemy sorcerer who is using distance spells, but it might affect its allies if they charge forward.
To-hit rolls: 13 , 26 (from Game Log)
Damage rolls if needed: 11 bludgeoning plus 3 radiant, 6 bludgeoning plus 1 radiant )

Varlan Con: 15, Varlan Dex: 8 (in log)

The wave buffets Varlan, but he remains unmoved. however it seemed to distract him from the second spell. Just as the lightning strikes, a magical barrier appears around him absorbing some of the energy and  seemingly supercharging his already electrified fists.

The wave buffets Varlan, but he remains unmoved. He catches sight of the lightning bolt as it runs along the course of the wall behind him, his focus now on the sorceror-warrior that cast it.

Mist's CON save: 21
Mist's DEX save: 4

Mist is unconscious.

EDITED, I had to reroll some stuff, I took the lower number for everything, I didn't want to punchish any players for the stupidity of the dice log.

The 5 of the other 9 close in and start to attack while the remaining stay back and ready an action to attack if anyone tries to flee. (3 of the 5 who closed the distance have harpoons the other 2 do not.  3 of the 4 that stay back have a harpoon.)

the 5 that move forward will attack 2 at Jecob, 2 at Varlan and 1 at Kraven. 

at Jecob Bite Attack: 14 Damage: 7 Claw Attack: 7 Damage: 7

at Jecod Bite Attack: 10 Damage: 9 Harpoon Attack: 21 Damage: 8

at Varlan Bite Attack: 10 Damage: 5 Claw Attack: 12 Damage: 9

at Varlan Bite Attack: 24 Damage: 5 Harpoon Attack: 13 Damage: 7

at Kraven Bite Attack: 9 Damage: 10 Harpoon Attack: 22 Damage: 7

At this it is your all turns.

Seeing the incoming death blow from the merfolk, Kraven reacts quickly thankfully deflecting most of the attack but not all of it as he dives out of the way to the side of Mist, gulping in seawater to help heal himself.

Reaction: Uncanny dodge to half the incoming damage.

BA + Move: Disengage and then move to Mist's side while pulling out his last healing potion.

Action: Seawater of Healing - 6

(( @dm: the numbers for the second attack on Varlan must be wrong. 2d6+4 can't make 19, and it's not a critical. The dice roller is someone's isn't broken -- everything is showing 7d6??? ))

Varlan plans to use a bonus action to drag the caster to withing 5' of the party (he's 10' now); but waiting on resolution of the weird dice rolls.

Reopening his eyes, Mist looks down at his torso and feels it in several places with both hands with a wide-eyed smile, clearly elated that he wasn't done for. Yet, anyway.

Following Varlan's line of sight and making an intuitive leap that has absolutely nothing to do with meta knowledge, Mist points a finger at the merrow caster who just attempted to fry his friends and a disorienting spike of psychic energy drives into the aggressor's mind! You can't see psychic energy so you'll just have to take his word for it.

The spectral tentacle whirls around and thuds down at the caster in the midst of the bedlam.

Action: Mind sliver - Int save DC 16 or take 6 psychic damage and subtract 1d4 from the next saving throw he makes before the end of my next turn.
Bonus: Tentacle of the Deeps - Attack: 15 Damage: 2 cold + slow etc.

3

WOW.

As a free action, Mist cowers behind Jecob a quiet squeak comes out. But not from his mouth.

Still glaring at the sorceror, Varlan focuses his will upon him, dragging him 5' closer to the party, putting him within melee range. He then strikes at the sorceror.

Attack: 23, Damage: 7
Attack: 23, Damage: 6

(( If that hits, then if they makes an attack roll at anyone other then Varlan, they will be at disadvantage ))

2