(Dobin is still up.)

Initiative Order:

1. Nivi
2. Dobin
3. Swarm (3)
4. Najax
5. Swarm (1)
6. Brand
7. Swarm (4)
8. Davak
9. Giant Spider
10. Swarm (2)
11. Ettercap

Dobin is able to avoid the fangs but is hit hard by the creatures claw. He swings back with his sword. His panther then strikes out. 

Action: Attack: 10 Damage: 8

Bonus Action Panther Attack: 6 Damage: 10

OOC:  Dobin, did you roll the first attack against the Ettercap with advantage?  Nivi's owl familiar provided help.  If we're using flanking rules (?), then the panther would also have had advantage due to flanking with Nivi who is now just NE of the Ettercap.

(OOC Cool Thanks)

2nd rolls for each:

Dobin: Attack: 15 Damage: 11

Panther: Attack: 16 Damage: 8

(Sorry for not answering the flanking question earlier but its a no. If I give it to the party then I also give it to the mobs as well. Just to avoid the whole gang-up scenario. But will still take the 2nd rolls for the attacks)

Nivi heads back into the room to see most of the party covered in spiders and a strange monstrosity tower over Dobin, its claw red with the drow's blood. She lunges for the creature stabbing into its stomach. Dobin joins as well, retaliating with slash of his own, not caring for the spiders on his person, his panther following his action. The creature hisses back as it finds itself faced with three now.

The spiders on the Dobin try to bite him once more.

Attack: 21 Damage: 10

(Najax is up)

OOC:  @TikoTee - thanks for the clarification on flanking!  Sounds good.  I had another question on damage to the Ettercap in the sea-wolves discord.

Dobin falls (will start Death Saves. Those Spiders pack a punch... or bite)

(Dobin is still good, you only took 37 damage total. I do update your hp after monster attacks so no need to apply changes.)

(Oh, Cool, Not Dead is always a good thing)

（ Let's make a Athletic Check to see if Najax can pull his great sword out.)

Athletic: 17

(Oh Please! )

Athletic:  10

Again, Najax failed to pull his weapon from the statue.

" Ughhh! This thing is cursed! Daming demon bugs! "

The Dragonborn shacks the swarm of spiders from his body. Two steps backward, he raises the great sword with the evil statue attacked and smashes the spiders like a sledgehammer!

At the same time, the tentacle floating in the air attacks the swarm too.

Free Action: Moves 5ft away from the swarm. Come on opportunity attack! 

Action: Attacks with the evil statue as improvised maul. (I added proficiency bonus. DM, if you feel inappropriate, please subtract the number ):  Attack: 14 Damage: 14

Divine Smite (if the attack hits): 10

Bonus: Tentacle of the Deeps: Attack:  20 Damage: 7

As Najax shakes off the spiders trying to step back, the spiders bite at him.

Attack: 21 Damage: 11 to Najax

Najax strikes at the spiders with his sword still stuck in the altar. taking a few out. But burst of divine energy takes more out as his tentacle assists as well, swatting out a few spiders. The spiders upon Brand traverse the sticky bonds with ease as the genasi had turned into easy prey for the swarm.

Attack: 23 Damage: 8 to Brand

Brand senses the spiders trying to bite him but his magical protection still keeps him safe even as the webbing restricts him. He tries to break free of the webbing ((Str Check: 3, rolled in Log)) but fails quite miserably. His magical protection would only protect him so much. Even for tiny mouths there were ways the magic could be broken through. He had other magic to help protect him - but that spell was brief and every such spell was taxing. Not knowing what else they were to face on this ship, he could not afford to waste all his energy here. That being said, he'd prefer to not die here.

"Uh, can I get some help out of this, please?" He called out to any ally who could hear as he twisted in place in his futile attempts to break free. 

(NOTE: While restrained, if the next attack would hit him, Brand would use a 1st level Shield spell to increase his AC by 5 (to 22) until the start of his next turn. If you need to put on a reminder when used, in case of further attacks, in the Effects container in his inventory is an item 'Shield Spell', just equip that to increase his AC by 5)

Despite moving away from the swarm, Najax finds the same swarm crawling back onto him, trying to bite him again.

Attack: 12 Damage: 10

(Davak is up)

Davak steps between the swarm and the giant spider, longswords swinging at both.

Attack (swarm) 19 - 9 damage

Offhand attack (giant) 16 - 4 damage

He grunts, and his swords swing yet again. (Action Surge, same targets)

Attack 21 - 6 damage

Offhand attack 13 - 7 damage

Davak steps between the giant spider and Brand, ignoring the swarm on him as it tries to bite him.

Attack: 4 Damage: 11

Davak's swords cuts through both the swarm and the giant spider. While the swarm moves defensively for their prey, the giant spider hisses at Davak, charging at him with its fangs.

Attack: 25 Damage: Unable to parse dice roll.

(If hit, Con Save 11, on fail take 12 poison damage, half on success. Davak has advantage and resistance as its poison, so on fail only 1/4 of damage, on success no damage.)

The swarm that was on Davak moves back onto him, biting at him once more.

Attack: 18 Damage: 14

The ettercap recoils a bit at the flurry of damage it took. It looks Nivi and shoots a web from its mouth.

Web Attack: 10

(If hit, target will be in same condition as Brand.)

Nivi's ducks away in revulsion from the Ettercap's foul webs, barely managing to avoid them (AC 16) and spitting out a stray strand of rotten silk from her mouth.  She looks disgusted at the party's choice of tactics thus far.  If we choose to fight slow swarms in tight quarters and not disengage and draw them out, then truly we deserve Tymora's curse and not Tymora's blessing.

She is torn between helping Brand and trying to finish off the Ettercap.  In the end, the selfish, ornery rogue in her wins out.  "Can someone please help fire boy get unstuck?  Or fire boy, can't you do that misty teleport I've seen my damn, oh-so-enchanting sister do when she's in a pinch?"

Her owl Shiv flies in the Ettercap's face again, flapping his wings and taking the help action, then back to Nivi's shoulder using his Flyby capability.

Nivi attacks the Ettercap with her rapier and Booming Blade, at advantage due to help and 3d20s due to Elven Accuracy:
To Hit Ettercap:  19
Rapier and Sneak Attack Damage:  1d8+4 + 2d6 = 5 (min) + 10 = 15 piercing damage
Secondary Booming Blade damage if Ettercap voluntarily moves:  4 thunder damage

Bonus Action:  Nivi disengages using Cunning Action and steps 5' east next to Brand and north of Dobin and Najax.  She would much rather use the rest of her movement to hit-and-run out the door again as the whole party should have done earlier, to her way of thinking.  But instead, she grudgingly makes enticing movements, staying in one place, hoping that the spider swarms attack her instead of one of her more injured companions.

Shiv the owl uses more of his 60' fly speed and Flyby capability to fly out the door and 10' up in the air to avoid the swarms, wanting no part of it.

Dobin works to escap/get rid of the swarm