FR PbP

(The water the party is standing in is about 18 in (48.26 cm) deep. The chasm, based on what's transpired, is considerably deeper, likely at least an entire level deep. )

( The party was traveling from the south of the level to the north expected a stair going up on the north side. INT 13+ assume the stair to be another 100 ft (30.48 m) )

Robwin considers the surge in the water to see if he knows that it’s unnatural ((Arcana: 18))…

Without another thought about it, Robwin casts web, planning to layer it across the floor (5ft deep), centred over the watery chasm, with the remainder of the 20ft cube (where possible) extending down into the crevasse, attempting to give his friends something to grab onto rather than being washed away, semi-blocking the chasm, and also giving any tentacles or creatures there a harder time moving and wailing on the party… “Hold on to the webbing!…”, he calls to his friends that are getting swept away. Steady in the water, he replants his feet before trying to move to safer/higher ground if possible.

While the others start moving across, Silenus keeps an eye out for the tentacles that appeared earlier, wondering if whatever the creature was that they belonged to was still alive.

(( What's the dex save for the Aboleth tentacles on the web? ))

((My bad, sorry yes of course. DEX save DC15. Thanks))

18 

While the tentacles are unimpeded by the webbing, it does allow for the others to get up out of the water and start moving toward Silenus. 

Tentacle attacks 

Against TT to hit Unable to parse dice roll.

Against Glin to hit Unable to parse dice roll.

Against Eline to hit Unable to parse dice roll.

Top of the round! 

Round Order but toss out what you're doing and we'll patch it together!

Rinn: ÷ Ini 21 

Aboleth layer

Eline ÷ Ini 19

TT ÷ Ini 16

Sudryl ÷ Ini 16

Valindra ÷ Ini 16 /w Dwarfs 

5 mountain dwarf ÷ Ini 16

Siv, Vil, Ird, Tra, Glin 

Shanyrria (f. Cleric lvl 3) ÷ Ini 14

Yian ÷ Ini 13

Silenus: ÷ Ini 9

Robwin ÷ Ini 5

Aboleth

((Is the Aboleth visible, besides the tentacles? Or is there at least look to be a central spot where the tentacles are coming from? Figuring out what Silenus's move is - helping everyone out vs teleporting to right on top of the aboleth and distracting it while the others get out of the water))

Rinn fires another arrow at one of the tentacles that hinders or holds one of the others to try and help them get free and away from the creature.

Longbow Attack: 27 Damage: 7

Sneak Attack if applicable: 13

On his turn, Robwin holds his +1 focus moon egg, then fires off a 1st level magic missile at the monster, while trying to manoeuvre round safely, at a distance from the tentacles, towards where the party are all heading ((13 force damage)). 

(( The tentacles appear to be from a central location, however they're also functioning independently. I believe only Rinn and Robwin know for certain. ))

Silenus, still in the midst of his magic over exuberance, takes a chance and teleports to right over top of what looks like the center of the aboleth and lets himself drop down from above, slashing twice with his great axe at whatever part of the creature he can lay into.

Bonus Action - Wild Surge - Teleport up to 30'

Action - Attack 1: Attack: 25 Damage: 9   including rage damage

Action - Attack 2: Attack: 20 Damage: 10  including rage damage

All three attacks hit. 

The rest of the party is using the webbing to get to the north side or out of the water and to the north side.

(( Rinn and Robwin, I believe, are still on the south side. ))

The tentacles swing out along the webbing. 

To hit 26 Eline (dmg 10)

To hit 16 TT (dmg 15)

To hit 27 Shanyrria (dmg 13)

Robwin will make his way, out wide, around the room as safely as possible, to where the rest of the party are congregating, ideally out of the water and a distance from the creature. When it comes back to his turn, he will shoot something at the monster (not fire due to the webbing, for now).

On his turn he cases mind sliver INT save DC15 or take 13 (psychic damage)