Shipwrecked in Saltmarsh

Dain can't quite land a solid hit on the walking corpses below. They begin to snarl and howl. "Meat!" they cry, "Food!"

Katernin is up next!

Katernin starts making her way down the rope, holding up her shield she proclaims. "Undead monstrosities, begone with you!"

Action: Channel Divinity Turn Undead
Any Undead within 30 feet of Katernin need to make a DC 14 Wisdom Save or be turned for a minute

Bonus Action: Attack any Undead that aren't effected by the turned effect (if there are any, if not ignore this attack)
Attack: 10 Damage: 8

Katernin swings down the rope and calls upon the powers of Ehlonna to drive these dead things away. But she can sense a stubbornness about them. They resist the forces meant to repel them.

DC14 Wisdom Saves: #1: 15, #2: 6, #3: 15, #4: 20

(oops forgot two were Baned as well. Subtract 3 from Save #1) 

#3 is turned, and begins to race away. The others are just infuriated, their attention drawn to this interloping cleric. They shriek and growl. "Eat!" they cry again, staring at Katernin with dead eyes, this time using the word as a command rather than commentary.

Katernin's spectral whip lashes the air ineffectively.

#3 runs toward the stern, sloshing through the deep water in a panic to escape Katernin. (She may have an opportunity attack upon it.) 

The water is difficult terrain for medium-sized creatures to wade through. (Molo, on the other hand, is swimming.)

#2 continues its attempt to feast upon Molo:
Corpse #2: Bite Attack vs. Molo: 10  Piercing damage: 11

#4 claws at Katernin:
Corpse #3 (baned): Claws Attack vs. Katernin: 20  Slashing damage: 12 (and, on a hit, a DC 10 CON saving throw...)

#1, distracted from Molo by Katernin, turns and lunges upon Katernin as well:
Corpse #1 (baned): Claws Attack vs. Katernin: 16  Slashing damage: 13 (and, on a hit, a DC 10 CON saving throw...)

Kelnan may act if he chooses, or he can continue focusing on his ritual.

Katernin must succeed on a DC 10 Constitution saving throw or be paralyzed for 1 minute.
Then, if she's still able, she may use her opportunity attack.

Then, everyone but Kelnan may act again: Fi'Finella, Dain, Fianna, Katernin, Molo.

(To clarify: Corpses # 1 and #3 are baned. #4 is wounded. #3 is also turned.
Correction to last post: Katernin was attacked by #4 not #3, but I won't try to retroactively retract the bane penalty. Perhaps it was slightly affected by the turning attempt in the moment?)

Also: Molo gets an opportunity attack on #1 as well, if he has a reaction free.

     Fi'Finella, invisible, is going to fly around corpse #2 and poke it, shout at it, and otherwise try to distract it in an attempt to help Molo...

     Fianna is going to jump down into the lower hold to try to get a better look at her targets and then fire an Eldritch Blast at Corpse #4.

Eldritch Blast Attack: 10 Damage: 6

Kelnan realizes he is quite alone, his party members occupied farther away than he'd like given the invisible creature lurking about. He stows his book and proceeds to survey the scene. Seeing Katernin beset by walking corpses, he fishes some powdered silver and iron from his pouch, rubs it in his palm while speaking a short incantation, and drops prone so he can reach down and touch whatever body part might present itself to grant some defense versus the undead assailants.

Protection from Evil and Good

Molo swings his scimitar at the fleeing ghoulie 

Attack: 8 Damage: 2 

On his turn he yells “Pull it up! I can take ‘em!”

Then swings his scimitar at Corpse 2

Attack: 23 Damage: 6 

Molo swings ineffectively at Katernin's attacker, even as he prepares a better-aimed swing at his own.

Meanwhile, Katernin is battling the effects of the claws that pierced her armor. CON Save: 19
She succeeds in overcoming the paralyzing effects, and chooses not to take a hasty swing at the turned creature (which would end the turning.)

Kelnan drops his ritual and rushes over to the cargo hatch. Dropping prone and reaching down, he slaps Katernin on the shoulder to give her added protection from. (Protection from Evil and Good)

 Fi'Finella, invisible, flies around and harasses corpse #2, currently threatening Molo. 

Fianna fires another arcane beam of energy, but can't seem to land a hit on the surprisingly agile corpses.

Molo swings a well-aimed blow on #2, causing a disgusting gash in its shoulder.

The fumes coming off these foul undead are overpowering. Molo and Katernin must make a DC 10 Constitution saving throw or be poisoned until next turn.

Dain and Katernin may act next, and Molo and Katernin should make DC10 CON saves.
(#1 (baned) and #4 (wounded) are within melee range of Dain and Katernin.)

Molo con save 3 

Dain stays prone in the upper level and swings at the ones below.  He's going to attack the wounded one (#4) first and if that hits and kills, will use his bonus action to attack the baned one (#1).

Action: Reckless Power Attack on #4: 18 Damage: 21
Possible Bonus Action: Reckless Power Attack on #1: 3 Damage: 21

Molo is nearly overcome with the fumes of the rotting bodies. He is poisoned through at least his next turn. 
Katernin similarly battles the stench. CON Save: 14

Fortunately, she has a draft of fresh air above her.

Dain makes a wild swing at corpse #4, and nearly tears its head clear off its shoulders. Somehow it still stands - barely.

Katernin may act next. She is protected somewhat by Kelnan's spell, and has two immediate foes in front of her: #1 (baned) and #4 (badly wounded).

Katernin nods her thanks to Kelnan and turns her focus to the undead in front of her. She swings alongside her spiritual weapon.

Action: Handaxe Attack
Attack: 5 Damage: 7

Bonus Action: Spiritual Weapon Attack
Attack: 9 Damage: 11

Katernin deftly cuts down corpse #4. Its foul body sinks beneath the oily waters. One down.

The undead creatures respond:

#1 (baned) vs. Katernin (Protected): Bite Attack: 2 Hit: 13 piercing damage.

#2 vs Molo: Claws Attack: 8 Hit: 6 slashing damage and a DC 10 Con saving throw or be paralyzed.

#3 continues to flee to the far corner of the stern.

Molo goes down, his little body bobbing face down in the water. 

Everyone may act, starting with Kelnan (who is still concentrating on his protection spell on Katernin)

     The invisible Fi’Finella can’t help Molo now so they go over to #1 and try to pester and distract it to hopefully give Katernin advantage on her next attack.. 

     Fianna gasps at seeing Molo fall and rushes over to him and casts a 2nd level [spell]Cure Wounds[/roll] upon him for 9 healing.  She’ll then just try to shield him until he can get back into the game…

Kelnan stands and circles the opening, lining up a Ray of Frost on #1.

Attack: 26 Damage: 9

Kelnan fires a blast of icy white magic at the head of Katernin's attacker, causing a serious, icy wound along its torso and leg. It is wounded, but suddenly free of Molo's bane. It is also harassed by Fi’Finella, giving Katernin an opening.

Unable to climb down the rope without provoking an opportunity attack by the corpse, Fianna jumps into the murky water to port. Dex check: 14

 She lands with a splash, and quickly wades over to Molo. He is revived, although still temporarily poisoned. 

Suddenly, a massive concussion impacts the ship. Did it hit something? The entire boat is slammed toward starboard, and the liquid contents of the hold turn into a lateral wave sloshing across. Everyone make a DC 15 Acrobatics check or be knocked over. (#1, #2, and #3 corpse saves: 18  16, 6 )

Dain, Katernin (protected), and Molo (conscious but poisoned) may act next.

Molo acrobatics 7 

12 - Fianna Acrobatics.

Molo, Fianna, and the box (still tied) get tumbled in the churning water. ("Prone" movement penalty applies, but not attack effects. Molo is swimming.)

Dain, Katernin (protected), and Molo (conscious but poisoned) may act next.
Kelnan, Katernin, and Dain should roll a Dex Save as well (and if Kelnan rolls below 8, he falls through the hatch.)

Molo spits and blisters. “Enough, you bony bags of waste!” 

And casts shatter at 1 and 2 while avoiding his allies

DC 14 Con save for half of 16 thunder damage