Beegred agrees with Tozer's advice. "I can't see in the dark, so it works for me to stay as a group as long as it is convenient."

"I've already stated my intentions," says Xilyrah, "And I can see in the dark, so stay close to me ranger, if you wish."

The party hastily voices their individual choices and eventually agree to take the southern route, bypassing Gracklstugh to get to Silverlight Grove.  Buppido vows everyone is going in the right direction, as per the divine plan.  Shuushar bows reverently to everyone saying he must return to Sloobdulop urgently and leaps into the water, disappearing below the surface.  Ront makes a brave show of deciding to follow the group in order to join Buppido when he splits towards Gracklstugh.  Derendil and Ferriman don't have any choice, as they are unconscious.  Eldeth and Jimjar look to each other and concede in stopping in Silverlight Grove before going to Blingdenstone.

With the decision made, Sarith stands to begin leading the way, but...

Stealth roll: 20

Everyone is surprised by a sudden telepathic blast screaming "Flesh for the Faceless Lord!" as a sickening slopping liquid slap hits Ferriman lying prone and unconscious next to the water...

DID THIS WRONG!  Below will happen on its turn, but in proper initiative order.  However, you are all surprised.  Per the PHB:

If you're surprised, you can't move or take an action on your first turn of the combat, and you can't take a reaction until that turn ends. A member of a group can be surprised even if the other members aren't.

Attack: 14

Which is an automatic crit and 2 death saving throw fails for Ferriman.

(Manipulated dice rolls because I deleted the damage die before I clicked Save Changes during an edit...!?)

ROLL INITIATIVE.

"Not a minute's rest!" barks Tozer.

• Initiative: Tozer: 20 | Eldeth: 3  | Jimjar: 16 

(I don't see Beegred. I hope he is not at I-6 !)

Init rolls - Beegred: 23, Sarith: 9, Ront: 12

Oops. Two Buppido's.  Beegred is at H5.

Narstin initiative: 12

Not going to bother rolling Derendil unless he wakes up by some miracle

Xilyrah Initiative:13

Buppido Initiative:7

Valthana, blind in the darkness, instinctively scoops up Stool and shields him from the direction of the noises (not a combatant).

Sarith, Tozer, Ront and Jimjar all observed the whip-like lashing of the pseudopod as it strikes down at Ferriman with a sickening slopping liquid slap as he lies motionless next to the water's edge. (To-Hit was rolled in post #626.  Automatic critical, Ferriman suffers 2 death saving throw failures.)

(The characters above can use a Reaction if any are available and applicable.)

Everyone else is caught completely unawares and are surprised by the attack, unable to react at all.

(Sarith, Tozer, Ront and Jimjar can act).

Sarith and Ront do not have Reactions they can use.

Sarith: casts Dancing Lights to make a humanoid shaped light at J7. Maybe it will distract the ooze? At the least, it will light up the target. He then moves to C6, readying his crossbow for next round.

Ront: was about to pull Ferriman away... but maybe that would that put him in range to get attacked. Sounds dangerous. Not to mention, that halfling was covered with excrement before the plunge into the river... Ront moves to E4, saying to anyone that will listen that he will help protect Stool.

Sarith casts Dancing Lights, forming a humanoid behind the ooze, above the water.

(I checked, this Ooze is naturally blind and does not rely on sight to sense its surroundings.  The light will not affect/distract it, but it will illuminate it for the others.)

Ront moves away westward saying, "Bring little one here.  We protect here."

(Good job embracing Ront's nature...)

Jimar leaps over Ferriman and takes a swing at this new foe with his war pick...

• War pick attack: 9 | Piercing damage: 4

Tozer, steps around Derendil and rears back with his maul, hoping to splatter the ooze into a hundred bits...

• Maul attack: 13 | Bludgeoning damage: 8

Jimjar (moves to J5) and Tozer (moves to H7) both strike valiantly at the formless blob of ooze threatening Ferriman and connect solidly.  The shape jiggles as the shock waves bounce around in its body, but it continues to maintain its form.  With another mind blast, "Flesh for the Faceless Lord!" it once again lashes out at Ferriman…

Ooze attack 5

… and the jiggling of its body causes it to miss its strike.

(Xilyrah, Narstin, Buppido, Beegred, and Eldeth can act.  Then Ferriman rolls a death save if applicable.)

 Seeing Ferriman once again in a bad state, narstin kneels over the man and tries to stabilize him again.

Medicine: 6

(Doh)

Narstin kneels next to Ferriman.  The little halfling is covered in thick liquid which Narstin attempts to wipe away.  Immediately upon touching the liquid, Narstin feels it sizzle on his hands and he frantically wipes them on the dirt floor.  The ooze struck Ferriman directly in the face, the acid already dissolved the eye lids, nose, cheeks and ears.  Even with magical healing, too many vital sense are already destroyed.  Assuming it is even possible to halt death at this point with simple first aid techniques, Ferriman would live life without ever seeing light, hearing sound, tasting or smelling the surroundings.  Eating would be a chore without a tongue or cheeks.  

Narstin leans back knowing Ferriman is too far gone.  The strike was fatal.  The body is just catching up.

(Just flavor... nothing negative mechanics-wise other than failing the check).

(I am assuming it is under an hour since we jumped off the platform into the river).

Beegred: uses his bonus action to transfer Hunter's Mark to the ooze. "Say hello to my little friend!"

Action to slash with his short sword - Attack: 24 Damage: 9 (damage includes Hunter's Mark)

Beegred focuses all his attention on the ooze and slashes it nearly in half.  The ooze seems to be attempting to reform itself, but liquid keeps spilling out of the slash.  It does not appear to be fatally struck, but it is definitely not holding itself up well.

Eldeth is uncertain that her arrows will do much harm to this nearly-liquid enemy, but she quickly fire two shots from her longbow...

• Longbow attack 1: 9 | Piercing damage: Unable to parse dice roll.
• Longbow attack 2: 5 | Piercing damage: 9

"Attacking the weak and wounded! Pathetic!" she yells at the ooze.