The tentacle creature is blasted back, tentacles lashing about as they snap and reform. One of the skitterers caught in the blast had been hit by his previous wave, and two seems enough to do the job as its corpse is flung back in a haze of dust.

((I've cleared the dead bodies to reduce visual clutter.))

Gramps: 18 (restrained, disadvantage on saves, disadvantage on attacks not vs a skitterer)
Larry: 12 (disadvantage on saves, disadvantage on attacks not vs a skitterer)
Amorphous Thing: 12 (-55 acided, 3/6 tendrils occupied)
Bryn: 8 
Keller: 8
Robed One: 7 (-115) (invisible, location unknown)
BB: 5 (restrained, disadvantage on saves, disadvantage on attacks not vs a skitterer)
Bolt: 2 ( disadvantage on saves, disadvantage on attacks not vs a skitterer) 
Skitterers: 2 (X/X/-5 blind /-5 blind /X/X/? blind/? blind /? blind /-14/?/? || X/X/X/X/X/X/-6/?/?/?/?/? )  <-------<<

The five around Larry shake themselves as they clear their blindness and attack.

Bite Attack: 11 Damage: 5, WIS Save: 15
Bite Attack: 4 Damage: 7, WIS Save: 6 if a previous WIS save failed, advantage on attack 21 to hit
Bite Attack: 15 Damage: 7, WIS Save: 7 if a previous WIS save failed, advantage on attack 10 to hit
Bite Attack: 11 Damage: 6, WIS Save: 17 if a previous WIS save failed, advantage on attack 21 to hit
Bite Attack: 22 Damage: 6, WIS Save: 15 if a previous WIS save failed, advantage on attack 16 to hit

The first attack catches Larry unprepared, but as the second one comes in, he again surrounds himself with protective magic.

((Crit gets through and he fails his save, but shield prevents any of the others from hitting.))

57: Wild Surge

Ethereal flames lick up around Larry.

The three on Bolt attack her, chittering and gnashing their nasty little teeth.

Bite Attack: 6 Damage: 5, on hit WIS Save 18
Bite Attack: 17 Damage: 7, on hit WIS Save 8, if previous WIS save fail, advantage on the attack, 20 to hit
Bite Attack: 10 Damage: 7, on hit WIS Save 11, if previous WIS save fail, advantage on the attack, 15 to hit

 On the other side of the battlefield, the skitterers regroup and swarm BB and Gramps.

Bite Attack on BB: 4 Damage: 7, on hit WIS Save 5
Bite Attack on BB: 17 Damage: 8, on hit WIS Save 9, if previous WIS save fail, advantage on the attack, 8 to hit
Bite Attack on BB: 17 Damage: 6, on hit WIS Save 2, if previous WIS save fail, advantage on the attack, 11 to hit

Bite Attack on Gramps: 21 Damage: 6, on hit WIS Save 14
Bite Attack on Gramps: 22 Damage: 9, on hit WIS Save 5, if previous WIS save fail, advantage on the attack, 22 to hit
Bite Attack on Gramps: 9 Damage: 5, on hit WIS Save 10, if previous WIS save fail, advantage on the attack, 7 to hit

The second bite hits Bolt for 7 damage and she feels herself distracted and unfocussed, but manages even in that state to fend off the third bite.

BB avoids all three chomping bites!

Gramps would get hit by two of the bites for 15 damage, and would fail the WIS save (I took the liberty of rolling).

A bolt of crackling, warbling energy arcs down from the hillside, presumably from where the Robed One is now invisibly hiding, flashing towards Larry. The figure doesn't appear after casting the spell.

Attack: 25 Damage: 13

(Uses legendary action)

Gramps: 18 (disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on him have advantage until skitterers turn)  <-------<<
Larry: 12 (disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on him have advantage until skitterers turn)
Amorphous Thing: 12 (-55 acided)
Bryn: 8 
Keller: 8
Robed One: 7 (-115) (invisible, location unknown)
BB: 5 (disadvantage on saves, disadvantage on attacks not vs a skitterer)
Bolt: 2 ( disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on her have advantage until skitterers turn) 
Skitterers: 2 (X/X/-5 blind /-5 blind /X/X/? blind/? blind /? blind /-14/?/? || X/X/X/X/X/X/-6/?/?/?/?/? )

ray of sickness on tentacles with tides of chaos:
to hit 9/19:/ for 22dmg and DC16 con save or be poisoned

chaos: 42

Black attacks skitterer: 19 for 8dmg

((Gramps is at disadvantage from the skitterers (for not attackign them), so granting himself advantage would make it a flat roll, which would be the 9, correct?))

((ah right..))

Grandpa blasts a sickening ray at the tentacle creature, but its undulating mass splits and the beam passes through without striking flesh. He feels a surge of chaos, but it dissipates without any discernable effect.

Black chomps down on the skitterer injured by BB thrusting it back, but it still stands.

Larry, with no Robed Figure to attack, turns his attention to clearing his surroundings of skitterers. (Adv on first attack via tides, flurry of blows.)

Attack: 18 Damage: 12
Attack: 15 Damage: 10
Attack: 20 Damage: 11
Attack: 20 Damage: 11

His first blow slams down, dropping one into the dust, a swift jab followed by a lashing kick sends another to join it, while his final blow sends a spray of ichor across the dusty ground from one of the three still facing him.

The tentacle creature lashes out at the brave trio near it.

Attack on BB: 22, grappled and restrained if it hits.
Attack on Black: 10, grappled and restrained if it hits.
Attack on Gramps: 22, grappled and restrained if it hits.

BB manages to avoid the the grasping tendril, but Grandpa and Black both get hit.

((Tentacle critter still acided, if you want to roll damage on it Gramps. Also pausing to see if there is anything any of you want to do in light of who got tendril'd.))

((Larry and Bolt each have 3 skitterers on them, the Robed Figure has vacated, but is somewhere on the other rise, invisible. There are a total of 6 skitterers near Grandpa, Black and BB, as well as the Amorphous Tentacle creature. Where do you guys want Bryn and Keller to focus their efforts?))

Gramps: 18 (disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on him have advantage until skitterers turn)
Black:   (disadvantage on saves, disadvantage on attacks not vs a skitterer)
Larry: 12 (disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on him have advantage until skitterers turn)
Amorphous Thing: 12 (-55 acided)   <-------<<
Bryn: 8 
Keller: 8
Robed One: 7 (-115) (invisible, location unknown)
BB: 5 (disadvantage on saves, disadvantage on attacks not vs a skitterer)
Bolt: 2 ( disadvantage on saves, disadvantage on attacks not vs a skitterer, attacks on her have advantage until skitterers turn) 
Skitterers: 2 (X/X/X/X /X/X/-11/? /? /-14/?/? || X/X/X/X/X/X/-14/?/?/?/?/? )

((Shouldn't it be BB and Gramps that are hit; not Black?

Oh and Black would have used deflect attack on the attack on gramps for disadvantage! ))

Acid dmg: 14

((Huh, must have read those wrong! Thought Black had a disadvantage to use... 15 to hit Gramps.))

((That misses))

((So BB is currently restrained, but not getting chomped yet?))

((Well, since he's the only one to be grabbed, he'll be getting chomped!))

The acid continues to eat away, gobs of goo puddling to the dust.

The lone tendril to connect drags BB closer, again trying to draw him in and chomp his tasty flesh. 

Attack: 9 Damage: 24

He's entirely too squirmy, and pulls back as the maw clamps shut.