Shipwrecked in Saltmarsh

Slammed against the hull, Kelnan stands up (from prone) and makes his way across the listing deck to the bottom of the stairs, joining Molo. (The deck is difficult terrain; climbing the stairs will require a successful DC10 Strength check next turn.)

Dain (helped by Katernin if he wants to climb the rope) and Katernin may act next. (Then, I'll resolve Fianna's turn, above.)
Both should start with a DC10 dex roll to avoid being knocked prone 10 feet to port.

The vessel is actively sinking; the hold will be mostly submerged by next turn.

Katernin continues to fly up and out, helping anyone else who is stuck in the meantime.

Dain:

Dex Save (+2):  7

 Dain falls over and slides away from the rope.  He then clambers to his feet and struggles back to the rope and tries to climb up it as far as he can with Katernin's help.

Athletics Check with Adv:  14

After helping Dain, Katernin flies straight up the stairs, through the webbed cabin, and up over the outside deck. She can see the ocean boiling on the (low) port side from whatever is underneath that possesses those tentacles; over the (high) starboard side she can see the dwarves waiting in their skiff some 200 feet off, looking unaware of what's happening; beyond it - some 500 or more feet away, lay the Soul of Winter, its sails down. Fianna is just outside her view, but Katernin can hear the commotion as Fianna scrambles on the side of the tilted vessel to rescue the falling crate.

Dain is able to regain his footing in the rapidly flooding hold and scramble up the rope. He joins Molo and Kelnan on the lower deck.

--Top of the round --

Fianna heals her wounds before leaping into the ocean to catch the sinking box.

Unseen doors in the cobwebbed lower deck, on both sides of Dain, fly open nearly simultaneously.

A figure in black, flanked by two massive spiders, emerges from the webs on one side; foul horrors - mostly mouth, and not of the natural world, crawl out of some forward cabin.
Added initiative:
Robed figure: 10
Giant spiders: 6
Crawling mouth horrors: 0

"Meniň ýolagçy gämim doly!" roars the figure in a language you do not recognize. (Dain Int check: 10 

(...Dain recognizes it as something akin to Goblin; maybe Orc?)

 -> Dain may act next (also Fi'Finella, if desired.)

The box is sinking. Unless Fianna can get some help, or unless she can make a DC 20 Strength (Athletics) check in her upcoming turn, the box (and her, if she's trying to hold it) will sink 20 feet. 

Dain moves behind Molo and Kelnan, protecting them as they flee up the staircase.   He will put himself between them and the creatures who are coming out towards us and dodge, holding his heavy maul at the ready.

Fianna strength check: 14 she cannot possibly make but let’s see how close she gets…

Edit - Fianna uses her Favored by the Gods class feature to add 2d4 errrr, no.  That’s got a saving throw, not a check.  Never mind.

     Fianna summons Fi’Finella to her so that the Imp can provide the help action to try to save the box?

     Fianna also summons Mage Hand to try to help.  It can only hold 10 pounds but maybe in conjunction with Fianna and the Imp?  All in all Fianna is refusing to give up on the box yet…

Dain carefully dodges the again-thrashing tentacles - DC10 Dex Save: 11
He then positions himself below Molo and Kelnan, preparing to protect himself and his comrades.

The strange, robed figure, grips the mast and bulkheads and storms forward, with purpose, toward Dain, Molo, and Kelnan, dodging the tentacles himself. (Dex Save: 18)

With a wave of his hand and an arcane word, he launches a deafening blast of thunderous force toward the three of you. Dain, Molo, and Kelnan: Make a DC12 Constitution Save, or take 11 of thunder damage and be thrown ten feet up the stairs. Katernin and Fianna hear the concussion but are not affected by it.
(On a success, take half damage.)

Katernin, Molo, and Kelnan may act next (start with a DC10 Dex Save to avoid the tentacles, then the DC12 CON save, except Katernin.) Dain may also roll his CON save.

Dain Con save (+5):   18

Molo con save 1 

 Molo falls unconscious and his body goes flying up the steps.

Katernin pauses in her flight at the sound, turning around to go help. Seeing Molo's unconscious body, she grabs him and some of the divine light that was helping her seeps into him, healing his wounds. She doesn't let go of him as she starts flying out of the ship with new purpose.

Action: Healing Hands: Molo regains 4 HP

Movement: Get Molo and herself out of there (if possible)

Katernin finds that the tentacles are on the top deck as well, grasping and smashing everything it reaches. DC10 Dex Save: 14

She successfully evades the snaking appendages. Hearing the new explosion, Katernin returns to the stairwell, still sporting her ghostly wings, and successfully revives him. (She is out of movement at this point. For the record, Molo weighs 28 pounds, but he's carrying a lot of gear. Should she want to fly him out, she is able to carry Molo, his armor, weapons, dulcimer, and immediate items, but his chest full of non-equipped items would need to stay behind.) 

Dain holds his ground (and takes only 5 points of thunder damage) and braces himself as the demons and spiders approach from behind the mysterious figure.

Kelnan may act next.  (Start with a DC10 Dex Save to avoid the tentacles, then the DC12 CON save vs. thunderous blast.) 

Kelnan

Dex save: 8

Con save: 11

Total damage: 19

Kelnan's magical ward shatters as he's battered by the tentacles, and blasted up the steps by a thunderous shockwave. He shouts at an unknown volume due to the noise "We want out of here just as bad as you!" and moves and Misty Steps as far toward the waiting ship as possible as memories of the previous shipwreck come flooding back.

Molo wakes under Katernin’s healing touch and sees the creeps closing in. He casts detect thoughts hoping to learn what he can, especially about any boat they may have arrived on or anything about calling off the tentacles, but currently only able to get surface thoughts 

Focusing first on the robed figure that nearly dispatched him, Molo initially detects desperation. He is angry at the group's intrusion, deeply frightened by the tentacles, and eager to find a way to escape this sinking ship, which has been his home for too long. He will kill as many of you as necessary to get up on deck and off this ship. (These are his surface thoughts; to learn more will require a second action.)

Kelnan races out onto the main deck, and is able to spot Fianna in the water with Fi'Finella and the sinking crate.

The pair of massive spiders crowd with the demons behind the robed figure. Only one of the spiders is able to strike out at Dain, who is prepared for the assault:

Spider Bite Attack vs. Dain: 18  Hit: 11 piercing damage (and a DC 11 CON save; take 72d8) poison damage on a failed save, or half on success.)

 Fianna (and Fi'Finella) and Dain may act next. 

(Fianna may see her post through above with the Mage Hand, unless she wants to change it. Fianna and Fi'Finella together are slowing the box from sinking into the sea, but the two are still struggling - Fianna must still succeed on a DC 15 Strength (Athletics) check or the box will sink. Mage Hand may help a little further...)

Strength Check: 15

     Fianna knows nothing about new antagonists inside the ship and assumes everyone is evacuating so sees her priority as trying to save the box. Mage Hand is all she has to possibly help so that is her plan...

Fianna, Fi'Finella, and Fianna's Mage Hand all strain to keep the box from sinking. They succeed for now, but unless they get more help, she will need to roll another DC12 Strength check next turn.

Kelnan sees that the two sailors in the skiff have spotted them, and are rowing toward the ship. But it will take some ten rounds for them to arrive.

Dain is up next!

Dain:

Seeing Fianna struggle with the box, Dain jumps into the water and heads over to try to help secure her and the box until either the rowboat arrives or the others can be saved.

Some housekeeping:

• My maps are at home; I'll get you the updated one Monday night or Tuesday. For now:
- Fianna is in the ocean near the (raised) starboard hull. She is (apparently, for now) safe from the tentacles, but is struggling mightily to not let the box sink. Fi"Finella is helping.
- Dain is at the bottom of the stairs singlehandedly holding back an explosive magic-user, two massive spiders, and a horde of mouthy demons.
- Kelnan is on the top deck (about where Katernin was in last-posted map), taking in the vistas of the boiling water on one side, and Fianna and the distant dwarves on the other.
- Molo is coming to at the top of the stairs, reading the robed guy's thoughts.
- Katernin is with Molo, considering whether to airlift him out of there.

• Remember everyone but Fianna must start their turn with a DC10 Dex roll or take 2d6 bludgeoning damage.
• Remember that the tilted deck is Difficult Terrain. Half-speed, essentially.
• Remember that climbing tilted stairs (like Dain will need to) is a DC 10 Strength (Athletics) check, or fall prone to the bottom.

The ship continues to shiver and rock as the tentacles continue to punch holes in it. The ship is sinking; water is beginning to appear on the lower deck, and the hold is fully submerged.

Dain DC 11 CON check vs poison: 11

 Fortunately, Dwal is well-built to handle poison. But he also tries to dodge tentacles: DC10 Dex save: 15 

 Lastly, he careens up the tilted stairs, past Molo and Katernin, scooping up Molo like a playground ball on the way (provided Molo is willing.) Dain is now at the doorway of the upper cabin; he can see Kelnan but not Fianna.